WO2008075865A1

WO2008075865A1 - Apparatus for manufacturing compacted irons and apparatus for manufacturing molten iron

Info

Publication number: WO2008075865A1
Application number: PCT/KR2007/006594
Authority: WO
Inventors: Myung-Chan Shin; Il-Hyun Cho
Original assignee: Posco Co Ltd
Current assignee: Posco Holdings Inc
Priority date: 2006-12-18
Filing date: 2007-12-17
Publication date: 2008-06-26
Anticipated expiration: 2009-06-18
Also published as: CN101563472A; CN101563472B; KR100784150B1

Abstract

An apparatus for manufacturing compacted iron includes at least one pair of molding rolls that compress fine iron and manufacture compacted iron. The pair of molding rolls include a shaft provided with a cooling passage, and a roll tyre that surrounds the shaft to be combined together.

Description

APPARATUS FOR MANUFACTURING COMPACTED IRONS AND APPARATUS FOR MANUFACTURING MOLTEN IRON

Technical Field The present invention relates to an apparatus for manufacturing compacted iron and an apparatus for manufacturing molten iron using the same, and more specifically to an apparatus for manufacturing compacted iron by compacting reduced materials containing fine reduced iron, and an apparatus for manufacturing molten iron using 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 role 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 coal as a raw material, are charged into a blast furnace together and oxygen is supplied thereto to reduce the iron ore to iron, and thereby manufacturing molten iron.

The blast furnace method, which is the most popular method used 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 coal 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 agglomeration 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 coal as a fuel and a reducing agent and by directly using fine ore, which accounts for more than 80% of the world's ore production.

An installation for manufacturing molten iron directly using raw coal and fine iron ore is disclosed in U.S. Patent No. 5,534,046. The apparatus for manufacturing molten iron disclosed in U.S. Patent No. 5,534,046 includes three- stage fluidized-bed reactors forming a bubbling fluidized bed therein and a melter- gasifier connected thereto. The fine iron ore and additives are charged into the first fluidized-bed reactor at room temperature and successively go through three- stage fluidized-bed reactors. Since hot reducing gas produced from the melter- gasifier is supplied to the three-stage fluidized-bed reactors, the temperature of the iron ores and additives, which were at room temperature, is raised by contact with the hot reducing gas. Simultaneously, 90% or more of the iron ore and additives is reduced and 30% or more thereof are sintered, and they are charged into the melter- gasifier.

A coal-packed bed is formed in the melter-gasifier by supplying coal thereto. Therefore, iron ore and additives at room temperature are melted and slagged in the coal packed bed and are then discharged as molten iron and slag. The oxygen supplied from a plurality of tuyeres installed on the outer wall of the melter-gasifier burns the coal-packed bed and is converted to a hot reducing gas. Then, the hot reducing gas is supplied to the fluidized-bed reactors, thereby reducing iron ore and additives and is then exhausted to the outside.

However, since a high-speed gas flow is formed in the upper portion of the melter-gasifier included in the above-mentioned apparatus for manufacturing molten iron, there is a problem in that the fine reduced iron and sintered additives charged into the melter-gasifier are scattered and loosened. Furthermore, when fine reduced iron and plasticized additives are charged into the melter-gasifier, there is a problem in that permeability of gas and liquid in the coal-packed bed of the melter-gasifier cannot be ensured.

In order to solve the above problems, a method for briquetting fine reduced iron and additives and charging them into the melter-gasifier has been developed. Relating to the above development, U.S. Patent No. 5,666,638 discloses a method for manufacturing oval-shaped briquettes made of sponge iron, and an apparatus using the same. In addition, U.S. Patent Nos. 4,093,455, 4,076,520, and 4,033,559 disclose a method for manufacturing plate-shaped or corrugated briquettes made of sponge iron, and an apparatus using the same.

Generally, the apparatus for manufacturing briquettes is provided with two roll tyres and hot fine reduced iron is transferred and pressed therebetween by force, and thereby grains with a size that is equal to or greater than a predetermined size are made. At this time, thermal stress occurs in the roll tyre due to hot fine reduced iron and then an installation is damaged by fatigue cracks that occur and grow during long-term use thereof.

DISCLOSURE Technical Problem

An apparatus for manufacturing compacted iron, which removes stress caused by high temperature and high pressure and prevents damage thereto, is provided.

Technical Solution

An apparatus for manufacturing compacted iron according to the present invention includes a pair of molding rolls that compress fine ore and manufactures compacted iron, and the molding rolls include a shaft provided with a cooling passage and a roll tyre that surrounds the shaft to be combined together.

The roll tyre includes a shoulder that surrounds the shaft and a concave portion that is partially formed on the shoulder, and the cooling passage may be arranged to correspond to an area in which the concave portion is formed.

The concave portion may be arranged to be in a center portion of a longitudinal direction of the shaft of the shoulder.

The cooling passage may be inserted into a center axis of the shaft and surrounds the shaft with a spiral form.

The molding roll may have a diameter in a range from 1200mm to 1400mm, and the roll tyre may have a thickness in a range from 140mm to 200mm. In addition, the apparatus for manufacturing compacted iron according to the present invention may further include a crusher that crushes the compacted iron that is manufactured in the molding rolls, and may further include a second crusher that controls a grain size of the compacted iron crushed in the crusher.

In addition, the fine ore includes fine reduced iron or additives. Meanwhile, an apparatus for manufacturing molten iron according to the present invention includes an apparatus for manufacturing compacted iron that compacts fine ore, and a melter-gasifier into which the compacted iron manufactured in the apparatus for manufacturing compacted iron is charged. The melter-gasifier melts the compacted iron. The apparatus for manufacturing compacted iron includes the apparatus for manufacturing compacted iron and at least a pair of molding rolls that compress fine ore and manufacture compacted iron, and the molding rolls include a shaft provided with a cooling passage and a roll tyre that surrounds the shaft to be combined together. Advantageous Effects

Damage to the molding rolls is reduced and a period between exchanging the molding rolls is increased by reducing stress in the apparatus for manufacturing compacted iron. Therefore, an operation time is prevented from being decreased by an exchanging operation and costs for exchanging the molding rolls can be saved.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of the apparatus for manufacturing compacted iron according to an embodiment of the present invention.

FIG. 2 is a schematic view illustrating a cooling passage of a molding roll. FIG. 3 is a schematic view of the apparatus for manufacturing molten iron according to an embodiment of the present invention.

FIG. 4 is a schematic view illustrating positions for measuring the stress in the Exemplary Example and the Comparative Example.

FIGs. 5 and 6 are simulated views of measured interference stresses of the Exemplary Example and the Comparative Example, respectively.

FIGs. 7 and 8 are simulated views of measured deformation amounts of the Exemplary Example and the Comparative Example, respectively. FIGs. 9 and 10 are simulated views of measured compressive stresses of the

Exemplary Example and the Comparative Example, respectively.

FIGs. 11 and 12 are simulated views of measured temperatures of the Exemplary Example and the Comparative Example, respectively.

FIGs. 13 and 14 are simulated views of measured thermal stresses of the Exemplary Example and the Comparative Example, respectively.

BEST MODE

Exemplary embodiments of the present invention will be explained in detail below with reference to the drawings. The embodiments of the present invention are merely to illustrate the present invention, and the present invention is not limited thereto.

FIG. 1 schematically illustrates an apparatus for manufacturing compacted iron 100 according to an embodiment of the present invention. The apparatus for manufacturing compacted iron 100 of FIG. 1 manufactures compacted iron by compressing and crushing fine ore, for example fine direct reduced iron (DRI). A structure of the apparatus for manufacturing compacted iron 100 is merely to illustrate the present invention and the present invention is not limited thereto. Therefore, a structure of the apparatus for manufacturing compacted iron 100 can be modified into other forms.

Particularly, even though the fine reduced iron is only shown to be charged into a charging device 11, this is merely to illustrate the present invention and the present invention is not limited thereto. Therefore, the compacted iron can be manufactured by compressing and crushing reduced materials, and the reduced materials may further include plasticized additives for plasticizing the fine reduced iron.

As shown in FIG. 1, the apparatus for manufacturing compacted iron 100 includes a charging device 11, a pair of molding rolls 20, a crusher 30, and a second crusher 40. Further, the apparatus for manufacturing compacted iron 100 may include a level controlling device 13, an open/ close valve 15, a charging hopper 25, and a guide chute 29, if necessary.

The charging device 11 variably controls an amount of the fine reduced iron that is charged from an upper side while discharging it into a lower side and supplying it to the pair of molding rolls 20 to be not more than 60ton/hr. As described above, since a large amount of the fine reduced iron can be treated, there is an advantage in that a large amount of compacted iron can be continuously manufactured. The fine reduced iron can be manufactured by passing a mixture of the iron ore and additives through a fluidized-bed reduction reactor. The fine reduced iron using the above method can be supplied to the charging device 11. The charging device 11 can store the fine reduced iron with a temperature of not less than 700 "C and a volume specific gravity of about 2ton/m³. Since the discharging pressure of a final fluidized-bed reduction reactor is about 3 bar and a flux thereof is about 3000m³/h, hot fine reduced iron is transferred to the charging device 11 by force. Although the compacted iron can be manufactured by only using hot fine reduced iron without plasticized additives, the amount of the plasticized additives is controlled to be in a range from about 3% to about 20% of the total amount of materials mixed with hot fine reduced iron in order for the hot fine reduced iron to not be easily broken in a melter-gasifier. The level controlling device 13 is installed at a lower side of the charging device 11. The level controlling device 13 detects a level of the fine reduced iron stored in the charging device 11, and blocks it from being transferred from the fluidized-bed reduction reactor or controls a transferring amount thereof if the amount of the fine reduced iron is raised to a predetermined level. In addition, the open/ close valve 15 is installed at a lower side of the charging device 11. The open/ close valve 15 includes an open/ close plate 15a for opening and closing a lower end of the charging device 11, and an oil pressure actuator 15b for controlling the open/ close plate 15a. An amount of the fine reduced iron transferring from the charging device 11 to the charging hopper 25 is controlled by using the open/ close valve 15.

The charging hopper 25 is located at an upper side of a gap formed between the pair of molding rolls 20, and charges the fine reduced iron into the pair of molding rolls 20. A large amount of compacted iron can be continuously manufactured by the pair of molding rolls 20 since the fine reduced iron is continuously charged from the charging hopper 25 as described above.

The pair of molding rolls 20 include two molding rolls 20a and 20b. The pair of molding rolls 20 are connected to the charging device 11 located at an upper side thereof, and they compress the fine reduced iron charged from the charging device 11. Since the two molding rolls 20a and 20b rotate toward a lower side in opposite directions to each other, a continuous stream of compacted iron can be manufactured by compressing the fine reduced iron.

Particularly, among the pair of molding rolls 20, the first molding roll 20a is installed as a fixed type and an axis of the second molding roll 20b is supported by an oil pressure cylinder 27 etc. in order to prevent malfunction thereof caused by charging a large amount of fine reduced iron. Therefore, the second molding roll 20b is a moving type and is installed to be movable along a horizontal direction with respect to the first molding roll 20a. Therefore, even if a large amount of the fine reduced iron is charged, compacted iron can be continuously manufactured since the second molding roll 20b can be elastically movable in a horizontal direction with respect to the first molding roll 20a.

Corrugated compacted iron is manufactured by operating the molding rolls 20 while offsetting protrusions formed on a surface of the first molding roll 20a with protrusions formed on a surface of the second molding roll 20b. Therefore, compacted iron can be easily crushed in a following process. When the compacted iron is manufactured using the-above described method, production efficiency is improved by increasing volume in a width direction of the molding roll. The corrugated compacted iron manufactured as described above is guided by using a guide chute 29 and is then coarsely crushed by the crusher 30. The guide chute 29 continuously guides compacted iron manufactured in the molding roll 20 to the crusher 30 without interruption.

The crusher 30 coarsely crushes the compacted iron. The crusher 30 can crush the corrugated compacted iron to have an average grain size equal to or less than 50mm. Here, if the corrugated compacted iron is crushed to have a grain size of over 50mm, a heavy load is applied to the second crusher 40, and thereby the second crusher 40 can malfunction. Therefore, the compacted iron is crushed to have an average grain size equal to or less than 50mm. As described above, the compacted iron is crushed to have an average grain size equal to or less than 50mm, and thereby it is manufactured into indeterminate forms to be suitable for use in the melter-gasifier of the following process. The coarsely crushed compacted iron enters the second crusher 40 and is then crushed again therein. The second crusher 40 is connected to a rear end of the crusher 30, and thereby coarsely crushed compacted iron is crushed again in the second crusher 40 and a grain size distribution of the compacted iron is controlled after the corrugated compacted iron is coarsely crushed in the crusher 30. The second crusher 40 controls a grain size distribution of the compacted iron by crushing the coarsely crushed compacted iron again using the pair of crushing rolls. The second crusher 40 includes a pair of crushing rolls 40a and 40b to be installed to be spaced apart from each other. The pair of crushing rolls 40a and 40b may be made of an integrated body or be divided as a disk type. As described above, if the compacted iron provided with a suitable grain size distribution is charged into the melter-gasifier, the compacted iron is supplied to the melter-gasifier and then melting performance and permeability thereof can be suitably maintained during melting and slagging processes. In addition, an oxygen tuyere attached to a lower side of the melter-gasifier is prevented from being damaged by being melted. Therefore, improvements of the efficiency and productivity of the process for manufacturing molten iron can be realized. An internal structure of the molding roll is explained in more detail with reference to FIG. 2 below.

FIG. 2 schematically illustrates the internal structure of the molding roll of FIG. 1 for explanation. Although the internal structure of the first molding roll 20a of FIG. 1 is shown in FIG. 2, the internal structure of the second molding roll 20b can be formed with the same structure. The first molding roll 20a is explained below and an explanation of the second molding roll is omitted.

As shown in FIG. 2, a cooling passage 22 is formed on a surface of the shaft 24 and the shaft 24 provided with the cooling passage 22 is inserted into an inner surface of the roll tyre 26. The roll tyre 26 is provided with a shoulder 26a surrounding the shaft 24 and a concave portion 26b formed on the shoulder 26a. The cooling passage 22 provided in the shaft 24 is arranged to correspond to an area on which the concave portion 26b is formed. More specifically, the concave portion 26b is formed on a center portion of a longitudinal direction of the shaft 24 of the shoulder 26a and the cooling passage 22 is installed at a lower side of a vertical direction where the concave portion 26b is installed.

As described above, the cooling passage 22 is installed in a direct lower side of the concave portion 26b and is not installed at the lower side of the shoulder 26a on which the concave portion 26b is not formed, and thereby a temperature difference caused by the cooling water is prevented such that it can prevent strength of the shoulder 26a from being reduced.

The cooling passage 22 is inserted into the center axis of the shaft 24, thereby being formed to surround the shaft 24 as a spiral type. Therefore, the cooling water enters the center axis of the shaft 24 and flows through a spiral shaped space between the shaft 24 and the roll tyre 26. Then, the cooling water is discharged in a direction opposite to the direction in which the cooling water enters.

The total diameter of the molding roll 20a including the shaft 24 and the roll tyre 26 may be in a range from 1200mm to 1400mm. At this time, if the thickness b of the roll tyre 26 is over 200mm, the cooling effect is reduced since the distance between the cooling passage 22 and the concave portion 26b becomes larger. In addition, if the thickness b of the roll tyre 26 is less than 140mm, strength of the roll tyre 26 is reduced due to thermal stress. Therefore, the thickness of the roll tyre 26 may be in a range from 140mm to 200mm. At this time, the thickness of the shaft 24 can be in a range from 1000mm to 1060mm. FIG. 3 schematically shows an apparatus for manufacturing molten iron

1000 according to an embodiment of the present invention. FIG. 3 schematically shows a process for manufacturing molten iron using compacted iron manufactured from the apparatus for manufacturing compacted iron.

As shown in FIG. 3, the apparatus for manufacturing molten iron 1000 further includes a hot transferring device 50 and the melter-gasifier 70 in addition to the above-described apparatus for manufacturing compacted iron 100. The compacted iron with a suitable controlled grain size distribution is supplied to the melter-gasifier 70 through the hot transferring device 50.

Crushed compacted iron is supplied to the melter-gasifier 70 through the hot transferring device 50 that is insulated from the outside in order to be maintained in a hot state for raising thermal efficiency. Since the structure of the hot transferring device 50 can be easily understood by those skilled in the art, a detailed description thereof is omitted.

Lumped coal or coal briquettes are supplied to the melter-gasifier 70. For example, the lumped coal can be coal with a grain size of over 8mm collected from a production site. As an example, the coal briquettes can be manufactured by compressing coal with a grain size equal to or less than 8mm by a press. The coal is collected from the production site and pulverized.

Lumped coal or coal briquettes are charged into the melter-gasifier 70 and then oxygen (O2) is supplied thereto, and thereby the compacted iron is melted and discharged through a tap. Molten iron with a good quality can be easily manufactured by using the above-described method.

The present invention is explained in detail with reference to an Exemplary Example of the present invention below. The Exemplary Example is merely to illustrate the present invention and the present invention is not limited thereto. Exemplary Example

Interference stress, compressive stress, and thermal stress of the molding roll were measured when a spiral shaped cooling passage was formed on an outer surface of the shaft. Specific conditions of the molding roll are described in Table 1 below. At this time, maximum diameters of the molding roll, the shaft, and the roll tyre in which the concave portion is formed were manufactured to be 1440mm, 1048mm, and 196mm, respectively.

Table 1

Comparative Example

To compare with the Exemplary Example, interference stress, compressive stress, and thermal stress of the molding roll were measured when a spiral shaped cooling passage was formed on an inner surface of the roll tyre thereof. Specific analytic conditions were the same as those of the Exemplary Example described in Table 1. At this time, maximum diameters of the molding roll, the shaft, and the roll tyre in which the concave portion is formed were manufactured to be 1440mm, 1000mm, and 220mm, respectively.

FIG. 4 shows measuring positions of the Table 2 and FIGs. 5 to 9 show analytic results of the respective stress. Measuring results are described in the Table 2 below.

Table 2

FIG. 5 shows an interference stress of the Exemplary Example, while FIG. 6 shows that of the Comparative Example. As described in Table 2 and shown in FIGs. 5 and 6, less interference stress was measured in the Exemplary Example compared to the Comparative Example except for the center portion of the roll tyre (position 4 of FIG. 4).

FIGs. 7 and 8 show deformation amounts and compressive stress of the Exemplary Example while FIGs. 9 and 10 show those of the Comparative Example, respectively. As shown in FIGs. 7 and 8, total deformation amounts of the Exemplary Example were less than those of the Comparative Example. Therefore, as described in Table 2 and shown in FIGs. 9 and 10, less total occurring stresses were measured in the Exemplary Example compared to the Comparative Example.

FIGs. 11 and 13 show temperature and thermal stress of the respective portions of the Exemplary Example, and FIGs. 12 and 14 show temperature and thermal stress of the respective portions of the Comparative Example. As described in the Table 2 and shown in FIGs. 13 and 14, the thermal stress of the

Exemplary Example was measured to be less than that of the Comparative Example.

As shown in FIGs. 11 to 14, the molding roll of the Exemplary Example in which the cooling passage is installed in the shaft and the thickness of the roll tyre is formed to be relatively thin has overall smaller stress comparing to that of the

Comparative Example. As described above, in a case that the cooling passage is installed on the outer surface of the shaft, the total stress could be reduced to be equal to or less than 50% compared to a case in which the cooling passage is installed on the inner surface of the roll tyre. Therefore, a period of exchanging the roll tyres can be largely increased by reducing a phenomenon in which cracks occur in the cooling passage due to the stress.

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 manufacturing compacted iron, the apparatus comprising a pair of molding rolls that compress fine ore and manufacture compacted iron, wherein the molding rolls comprise: a shaft provided with a cooling passage; and a roll tyre that surrounds the shaft to be combined together.

2. The apparatus of Claim 1, wherein the roll tyre comprises: a shoulder that surrounds the shaft; and a concave portion that is partially formed on the shoulder, wherein the cooling passage is arranged to correspond to an area in which the concave portion is formed.

3. The apparatus of Claim 2, wherein the concave portion is arranged to be in a center portion of a longitudinal direction of the shaft of the shoulder.

4. The apparatus of Claim 1, wherein the cooling passage is inserted into a center axis of the shaft and surrounds the shaft as a spiral type.

5. The apparatus of Claim 1, wherein the molding roll has a diameter in a range from 1200mm to 1400mm.

6. The apparatus of Claim 5, wherein the roll tyre has a thickness in a range from 140mm to 200mm.

7. The apparatus of Claim 1 further comprising a crusher that crushes the compacted iron that is manufactured in the molding rolls.

8. The apparatus of Claim 7 further comprising a second crusher that controls a grain size of the compacted iron crushed in the crusher.

9. The apparatus of Claim 1, wherein the fine ore comprises fine reduced iron or additives.

10. An apparatus for manufacturing molten iron, the apparatus comprising: an apparatus for manufacturing compacted iron that compacts fine ore; and a melter-gasifier into which the compacted iron manufactured in the apparatus for manufacturing compacted iron is charged, the melter-gasifier melting the compacted iron; wherein the apparatus for manufacturing compacted iron comprises the apparatus for manufacturing compacted iron, and at least a pair of molding rolls that compress fine ore and manufacture compacted iron, and wherein the molding rolls comprise a shaft provided with a cooling passage, and a roll tyre that surrounds the shaft to be combined together.

11. The apparatus of Claim 10, wherein the roll tyre comprises: a shoulder that surrounds the shaft; and a concave portion that is partially formed on the shoulder, wherein the cooling passage is arranged to correspond to an area in which the concave portion is formed.

12. The apparatus of Claim 11, wherein the concave portion is formed in a center portion of a longitudinal direction of the shaft of the shoulder.

13. The apparatus of Claim 10, wherein the cooling passage is inserted into a center axis of the shaft and surrounds the shaft as a spiral type.

14. The apparatus of Claim 10, wherein the molding roll has a diameter in a range from 1200mm to 1400mm.

15. The apparatus of Claim 14, wherein the roll tyre has a thickness in a range from 140mm to 200mm.

16. The apparatus of Claim 10 further comprising a crusher that crushes the compacted iron that is manufactured in the molding rolls.

17. The apparatus of Claim 16 further comprising a second crusher that controls a grain size of the compacted iron crushed in the crusher.

18. The apparatus of Claim 10, wherein the fine ore comprises fine reduced iron or additives.