EP2641981B1

EP2641981B1 - Method for manufacturing molten iron

Info

Publication number: EP2641981B1
Application number: EP11842354.0A
Authority: EP
Inventors: Myoung-Kyun Shin; Sang-Hoon Joo; Dong-Jin Kim; Jin-Tae Kim
Original assignee: Posco Co Ltd
Current assignee: Posco Holdings Inc
Priority date: 2010-11-19
Filing date: 2011-11-18
Publication date: 2019-06-05
Anticipated expiration: 2031-11-18
Also published as: KR101187851B1; CN104694687A; CN103221555B; EP2641981A4; CN103221555A; EP2641981A2; WO2012067462A2; KR20120054262A; WO2012067462A3

Description

Technical Field

The present invention relates to a method for manufacturing molten iron and, more particularly, to a method for manufacturing molten iron which is capable of performing molten iron work stably and efficiently by using a high-temperature compacted iron storage tank.

Background Art

In an apparatus for manufacturing molten iron which includes a multi-stage fluidized furnace and a multi-stage smelting furnace and directly uses fine or lump coal and fine iron-containing ores, if reducing gas is not sufficiently supplied from the smelting furnace to the multi-stage fluidized furnace, the formation of a fluidized bed is impossible, thereby making iron work impossible.
Accordingly, high-temperature compacted iron manufactured by the reduction and compacting of reduced fine iron in the multi-stage fluidized furnace is not supplied to the smelting furnace.
The above condition is generated when a sufficient amount of reducing gas for the multi-stage fluidized furnace is not supplied from the smelting furnace, that is, when a work is started or stopped, and is also generated when the amount of reducing gas generated is reduced due to a reduction of the smelting furnace attributable to smelting furnace work and equipment obstacles.
Furthermore, an interruption in the high-temperature reduced iron supplied to the smelting furnace is also generated when equipment for the multi-stage fluidized furnace or a high-temperature compacting apparatus fails.
If the supply of the high-temperature compacted iron to the smelting furnace is stopped, the amount of heat necessary to melt the reduced iron in the smelting furnace remains.
Accordingly, the smelting furnace is overheated, and smelting furnace work must be stopped. In order to prevent the problems, an additional iron source must be directly supplied to the smelting furnace. The additional iron source must be lump reduced iron because it has to be directly supplied to the smelting furnace. Accordingly, lump reduced iron is externally supplied in a conventional apparatus for manufacturing molten iron that directly uses fine or lump coal and ores containing fine iron ores.
As described above, the externally supplied lump reduced iron is more expensive than high-temperature reduced iron manufactured through a fluidized furnace, and it also increases a work cost for the apparatus for manufacturing molten iron. Furthermore, since the externally supplied lump reduced iron must be used in a room temperature state, amount of heat for a temperature rise in the externally supplied lump reduced iron is greater than that in the high-temperature reduced iron, thereby increasing the amount of coal necessary within the smelting furnace. As a result, a molten iron yield versus a design capacity is increased, and thus the productivity of the conventional apparatus for manufacturing molten iron that directly uses fine or lump coal and fine iron-containing ores is deteriorated.
CN 1842605 A and US2006/162499 A1 each disclose an apparatus for manufacturing molten iron comprising a fluidized bed furnace for converting fine iron ores into reduced fine iron by reducing fine iron ores; a compacted iron manufacturing device for manufacturing high-temperature compacted iron by compressing the reduced fine iron; a crushing device for crushing the high-temperature compacted iron; a first conveyance device for conveying the crushed, high-temperature compacted iron; a smelting furnace for melting the compacted iron by combusting fine or lump coal; a compacted iron storage tank for storing some crushed, high-temperature compacted iron; a second conveyance device for conveying the high-temperature compacted iron to the compacted iron storage tank; a 2-direction chute disposed under the crushing device; and a discharge device provided under the compacted iron storage tank and configured to convey the compacted iron away from the compacted iron storage tank.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

DETAILED DESCRIPTION

Technical Problem

The present invention has been made in an effort to provide a method for manufacturing molten iron having an advantage of increasing the stability and efficiency of a molten iron manufacturing process by manufacturing excess high-temperature compacted iron when normal work is performed, storing the excess high-temperature compacted iron in a compacted iron storage tank, and charging the stored compacted iron into a multi-stage smelting furnace when an abnormal work is performed in an apparatus for manufacturing molten iron using a multi-stage fluidized furnace and the multi-stage smelting furnace.

Technical Solution

Disclosed but not claimed is an apparatus for manufacturing molten iron, including a multi-stage fluidized furnace for converting fine iron ores into reduced fine iron by reducing fine iron ores, at least one compacted iron manufacturing device for manufacturing high-temperature compacted iron by compressing the reduced fine iron, at least one crushing device for crushing the high-temperature compacted iron at a specific granularity, a first conveyance device for conveying the crushed high-temperature compacted iron, at least one compacted iron storage tank for storing some of the crushed high-temperature compacted iron, a second conveyance device for conveying the crushed high-temperature compacted iron to the compacted iron storage tank, a third conveyance device, and a smelting furnace for melting the conveyed high-temperature compacted iron by combusting fine or lump coal and supplying reducing gas generated within the smelting furnace to the multi-stage fluidized furnace, wherein 2-direction chutes are disposed under the at least one crushing device, first outlets of the 2-direction chutes supply the crushed high-temperature compacted iron to the first conveyance device, and second outlets of the 2-direction chutes supply the crushed high-temperature compacted iron to the second conveyance device, wherein discharge devices are provided under the compacted iron storage tank and configured to supply the compacted iron to the third conveyance device, and the third conveyance device conveys the compacted iron to the first conveyance device, wherein the compacted iron storage tank comprises a level system for detecting an amount of compacted iron charged into the compacted iron storage tank.
A nitrogen supply pipe is disposed at the bottom of the compacted iron storage tank.
Furthermore, gas discharge pipes are disposed at the top of the compacted iron storage tank.
The gas discharge pipes are equipped with respective pressure control valves and configured to maintain pressure within the compacted iron storage tank higher than atmospheric pressure.
The apparatus for manufacturing molten iron further includes a carbon dioxide removal device for ramifying some exhaust gas discharged from the multi-stage fluidized furnace, removing carbon dioxide from the ramified exhaust gas, adding the exhaust gas to the reducing gas supplied from the smelting furnace, and supplying the added reducing gas to the multi-stage fluidized furnace.
The apparatus for manufacturing molten iron further includes a gas circulation cooling device for controlling temperature of reducing gas supplied to the multi-stage fluidized furnace by ramifying some reducing gas generated from the smelting furnace, cooling the ramified reducing gas, and circulating the reducing gas supplied from the smelting furnace again.
An exemplary embodiment of the present invention provides a method of manufacturing molten iron, including reducing fine iron ores into reduced fine iron by using the multi-stage fluidized furnace, manufacturing high-temperature compacted iron by compressing the reduced fine iron using the compacted iron manufacturing device, crushing the high-temperature compacted iron by using a crushing device, conveying the crushed compacted iron to a charging device, conveying some of the crushed compacted iron to a compacted iron storage tank, distributing the crushed compacted iron to the charging device or the compacted iron storage tank by using 2-direction chutes, and charging the compacted iron from the charging device into a smelting furnace and melting the charged compacted iron by combusting fine or lump coal wherein if the high-temperature compacted iron necessary for the smelting furnace is able to be manufactured through the multi-stage fluidized furnace, the compacted iron manufacturing device, and the crushing device, excess high-temperature compacted iron exceeding an amount of the high-temperature compacted iron necessary for the smelting furnace is manufactured, and the excess high-temperature compacted iron is intermittently conveyed to and stored in the compacted iron storage tank by way of an action of the 2-direction chutes, wherein if the high-temperature compacted iron necessary for the smelting furnace is unable to be manufactured through the multi-stage fluidized furnace, the compacted iron manufacturing device, and the crushing device, the compacted iron stored in the compacted iron storage tank is continuously supplied to the smelting furnace via a conveyance device, wherein if a ratio of a yield of high-temperature compacted iron manufactured by the multi-stage fluidized furnace the compacted iron manufacturing device, and the crushing device and demand quantity of high-temperature compacted iron necessary for the smelting furnace is defined by an excess rate as below, the excess rate = (yield of the high-temperature compacted iron)/(demand quantity of the high-temperature compacted iron) x 100, the excess rate is 110% to 120%.
The time that the high-temperature compacted iron stays in the compacted iron storage tank is 6 hours to 12 hours.

Advantageous Effects

In accordance with the method for manufacturing molten iron according to an exemplary embodiment of the present invention, by supplying means for efficiently supplying high-temperature reduced iron to the smelting furnace independently from means for reducing, compacting, and charging fine iron ores in the multi-stage fluidized furnace, the manufacturing of molten iron in the smelting furnace can be efficiently performed even when an initial work is performed or the operation of the multi-stage fluidized furnace is stopped due to the occurrence of an equipment obstacle. Accordingly, the productivity of a molten iron manufacturing device that directly uses fine or lump coal and ores containing fine iron can be improved.

Brief Description of the Drawings

FIG. 1 is a diagram schematically showing the construction of an apparatus for manufacturing molten iron using a compacted iron storage tank capable of storing excess high-temperature compacted iron.

Best Mode

The merits and characteristics of the present invention and the methods for achieving the merits and characteristics thereof will become more apparent from the following description of embodiments taken in conjunction with the accompanying drawing. However, the present invention is not limited to the disclosed embodiment, and may be implemented in various ways. The embodiment is provided to complete the disclosure of the present invention and to enable a person having ordinary skill in the art to understand the scope of the present invention. The present invention is defined by the category of the claims. The same reference numbers will be used to refer to the same or similar parts throughout the drawing.
Hereinafter, an apparatus for manufacturing molten iron is described below with reference to the drawing. For reference, in describing the present invention, a detailed description of known functions or constructions related to the present invention will be omitted if it is deemed that they would make the gist of the present invention unnecessarily vague.
FIG. 1 is a diagram schematically showing the construction of an apparatus for manufacturing molten iron using a compacted iron storage tank 600 capable of storing excess high-temperature compacted iron.
Referring to FIG. 1, fine iron ores are reduced to reduced fine iron by a multi-stage fluidized furnace 100, high-temperature compacted iron is fabricated by compressing the reduced fine iron, and the high-temperature compacted iron is crushed to a specific granularity.
The crushed high-temperature compacted iron is supplied to a first conveyance device 400 by using 2-direction chutes 700 in order convey the crushed high-temperature compacted iron to a charging device, and excess compacted iron is supplied to a second conveyance device 430 that is additionally provided so that the excess compacted iron is stored in a compacted iron charging tank. Accordingly, when a work is initiated or stopped, when a work obstacle is generated, and/or and when an equipment obstacle is generated, the stored compacted iron is supplied to a smelting furnace 500, thereby preserving the ability to manufacture stable molten iron.
Referring to FIG. 1, the apparatus for manufacturing molten iron includes a multi-stage fluidized reduction furnace for converting fine iron ores into reduced fine iron by reducing the fine iron ores, at least one high-temperature compacting apparatus for fabricating high-temperature compacted iron by compressing the reduced fine iron, at least one crushing device 300 for crushing the high-temperature compacted iron at a specific granularity, the first conveyance device 400 for conveying the crushed high-temperature compacted iron, and the smelting furnace 500 for melting the conveyed high-temperature compacted iron by combusting fine or lump coal and supplying reducing gas generated within the smelting furnace to the multi-stage fluidized furnace.
FIG. 1 illustrates a three-stage fluidized furnace 100, but this is only illustrative. The number of fluidized furnaces 100 can be three or more.
If the multi-stage fluidized furnace 100 has three stages, the first stage fluidized furnace 100 preheats fine iron ores, the second stage fluidized furnace 100 preliminarily reduces the preheated fine iron ores, and the third stage fluidized furnace 100 finally reduces the fine iron ores.
Secondary materials, such as limestone and dolomite, and an additive can also be charged into the multi-stage fluidized furnace 100 in order to prevent a phenomenon in which the fine iron ores are adhered to the inside of the multi-stage fluidized furnace 100 and prevent the reduced fine iron from being broken within the smelting furnace 500.
In order to compact the reduced fine iron ores before feeding the reduced fine iron ores to the smelting furnace 500, lump reduced fine iron is manufactured using a compacted iron manufacturing device 200. The compacted iron manufacturing device 200 manufactures compacted iron by compressing the reduced fine iron ores charged therein through a pair of rolls.
The high-temperature compacted iron manufactured by the compacted iron manufacturing device 200 is crushed to a proper granularity by the crushing device 300 disposed under the compacted iron manufacturing device 200 before the high-temperature compacted iron is charged into the smelting furnace 500.
The crushed compacted iron is supplied to the first conveyance device 400 through the first outlets of the 2-direction chutes 700 disposed under the crushing device 300.
The high-temperature compacted iron supplied to the first conveyance device 400 is conveyed to a charging device in order to be charged into the smelting furnace 500 and is continuously charged from the charging device to the smelting furnace 500. The smelting furnace 500 manufactures molten iron by melting the high-temperature compacted iron through the combustion of fine coal or compacted lump coal.
The smelting furnace 500 melts the compacted iron by combusting fine or lump coal using oxygen. At this time, reducing gas is generated. The smelting furnace 500 supplies the generated reducing gas to the multi-stage fluidized furnace 100 connected to the smelting furnace 500, so that reducing gas for reducing reduced fine iron is supplied to the multi-stage fluidized furnace 100.
The high-temperature compacted iron is supplied to the second conveyance device 430 disposed under the 2-direction chutes 700 through the second outlets of the 2-direction chutes 700. The high-temperature compacted iron is conveyed to and stored in the compacted iron storage tank 600 through the second conveyance device 430.
More particularly, the 2-direction chutes 700 are disposed under the at least one crushing device 300. The first outlets of the 2-direction chutes 700 supply the crushed high-temperature compacted iron to the first conveyance device 400, and the second outlets of the 2-direction chutes 700 supply the crushed high-temperature compacted iron to the second conveyance device 430.
Valves are provided in the respective outlets of the 2-direction chutes 700 so that the high-temperature compacted iron can be selectively supplied to the first conveyance device 400 or the second conveyance device 430.
Furthermore, a nitrogen supply pipe 610 is disposed at the lower part of the compacted iron storage tank 600, and gas discharge pipes 630 are disposed at the top of the compacted iron storage tank 600.
The gas discharge pipes 630 include respective pressure control valves 635 for maintaining pressure within the compacted iron storage tank 600 higher than atmospheric pressure.
That is, the nitrogen supply pipe 610 disposed at the lower part of the compacted iron storage tank 600 supplies nitrogen, and the gas discharge pipes 630 disposed at the top of the compacted iron storage tank 600 discharges gas. The pressure control valves 635 included in the gas discharge pipes 630 maintain pressure within the compacted iron storage tank 600 higher than atmospheric pressure so that the inflow of air from the outside can be minimized.
The compacted iron storage tank 600 further includes a level system for detecting the amount of compacted iron charged therein. The level system continuously measures the height of a high-temperature compacted iron layer formed within the compacted iron storage tank 600. Accordingly, compacted iron exceeding the capacity of the compacted iron storage tank 600 can be prevented from being supplied to the compacted iron storage tank 600.
Furthermore, the level system can detect the amount of high-temperature compacted iron stored in the compacted iron storage tank 600.
The apparatus for manufacturing molten iron further includes a third conveyance device 450. Discharge apparatuses 660 are disposed at the bottom of the compacted iron storage tank 600 and configured to supply compacted iron to the third conveyance device 450. The third conveyance device 450 conveys the compacted iron to the first conveyance device 400.
The apparatus for manufacturing molten iron can further include an exhaust gas reforming apparatus 800 for cooling gas discharged from the multi-stage fluidized furnace 100 via a water collector, ramifying some of the discharged gas, removing carbon dioxide from the ramified gas by compressing the ramified gas, mixing the ramified gas with high-temperature reducing gas discharged from the smelting furnace 500, and additionally supplying the mixed reducing gas to the multi-stage fluidized furnace 100.
Furthermore, in order to thermally decompose tar generated from fine coal or lump coal used in the smelting furnace 500, it is necessary to maintain a temperature of high-temperature reducing gas discharged from the smelting furnace at 500 1,000°C or higher and to lower a temperature of the high-temperature reducing gas to 700°C to 800°C necessary for the multi-stage fluidized furnace 100.
The temperature of the high-temperature reducing gas can be primarily cooled by mixing room-temperature carbon dioxide removal gas supplied from the exhaust gas reforming apparatus 800 with high-temperature reducing gas discharged from the smelting furnace 500.
The apparatus for manufacturing molten iron can further include a gas circulation cooling device 900 for ramifying some of the high-temperature reducing gas mixed with the carbon dioxide removal gas, cooling the ramified reducing gas via the water collector, compressing the cooled reducing gas, and mixing the compressed reducing gas with the high-temperature reducing gas so that a temperature of the mixed reducing gas is additionally cooled to temperature of the reducing gas supplied to the multi-stage fluidized furnace 100.
A method of manufacturing molten iron in accordance with an exemplary embodiment of the present invention includes the steps of reducing fine iron ores into reduced fine iron by using the multi-stage fluidized furnace 100, manufacturing high-temperature compacted iron by compressing the reduced fine iron by using the compacted iron manufacturing device 200, crushing the high-temperature compacted iron by using the crushing device 300, conveying the crushed compacted iron to the charging device, charging the compacted iron from the charging device into the smelting furnace 500, and melting the charged compacted iron by combusting fine or lump coal.
The method of manufacturing molten iron further includes the step of conveying some of the crushed compacted iron to the compacted iron storage tank 600.
The method of manufacturing molten iron further includes the step of distributing the crushed compacted iron to the charging device or the compacted iron storage tank 600 by using the 2-direction chutes 700.
If molten iron is normally continuously manufactured, that is, if high-temperature compacted iron necessary for the smelting furnace 500 can be manufactured through the multi-stage fluidized furnace 100, the compacted iron manufacturing device, and the crushing device 300, excess high-temperature compacted iron that exceeds the amount of the high-temperature compacted iron necessary for the smelting furnace 500 is manufactured. The excess high-temperature compacted iron intermittently discharges the high-temperature compacted iron from the crushing device 300 to the conveyance device by way of an action of the 2-direction chutes 700, so the high-temperature compacted iron can be conveyed to and stored in the compacted iron storage tank 600.
In contrast, in the method of manufacturing molten iron, if molten iron is not normally manufactured, that is, if high-temperature compacted iron necessary for the smelting furnace 500 may not be manufactured through the multi-stage fluidized furnace 100, the compacted iron manufacturing device, and the crushing device 300, compacted iron stored in the compacted iron storage tank 600 is discharged to the third conveyance device 450 via the discharge devices 660 and the third conveyance device 450 conveys the discharged compacted iron to the first conveyance device 400. Accordingly, high-temperature compacted iron necessary for the smelting furnace 500 can be continuously supplied.
In order to achieve the above operation, a yield of high-temperature compacted iron manufactured through the multi-stage fluidized furnace 100, the compacted iron manufacturing device 200, and the crushing device 300 must exceed demand quantity of high-temperature compacted iron necessary for the smelting furnace 500.
Assuming that a ratio of the yield of high-temperature compacted iron manufactured by the multi-stage fluidized furnace 100, the compacted iron manufacturing device 200, and the crushing device 300 and the demand quantity of the high-temperature compacted iron necessary for the smelting furnace 500 is defined by an equipment capacity excess rate as below, $Equipment capacity excess rate = (yield of high-temperature compacted iron) / (demand quantity of high-temperature compacted iron) \times 100,$
the equipment capacity excess rate can be 110% to 120%.
The range of the equipment capacity excess rate is based on that a ratio of the time during which an abnormal condition occurs in the entire operation time is about 80% to 90% in an apparatus for manufacturing molten iron that directly uses fine or lump coal and fine iron-containing ores.
Meanwhile, the reducing gas necessary for the multi-stage fluidized furnace 100 in order to manufacture the high-temperature compacted iron can be additionally supplied through a carbon dioxide removal device.
The time that the high-temperature compacted iron stays in the compacted iron storage tank 600 can be 6 hours to 12 hours.
Meanwhile, during a normal operation, high-temperature compacted iron may be stored in the compacted iron storage tank 600 excessively long. In this case, the high-temperature compacted iron can be cooled and may erupt. As a result, in an abnormal condition, the condition of the high-temperature compacted iron supplied to the smelting furnace 500 can be deteriorated.
In order to prevent this condition from occurring, high-temperature compacted iron stored at the lower part of the high-temperature compacted iron storage tank 600 may be partially discharged through the discharge devices 660, and the discharged high-temperature compacted iron may be periodically replaced with new high-temperature compacted iron manufactured and discharged through the multi-stage fluidized furnace 100, the compacted iron manufacturing device 200, and the crushing device 300.
The time that the high-temperature compacted iron is stored in the compacted iron storage tank 600 is regularly maintained through a series of the replacement processes, and the storage time may be 6 hours to 12 hours.
If the time is less than 6 hours, work and equipment expenses are inefficient because a large amount of high-temperature reduced iron must be supplied to the compacted iron storage tank 600 for the replacement and at the same time the amount of stored compacted iron corresponding to the large amount of high-temperature reduced iron must be discharged from the compacted iron storage tank 600.
In contrast, if the time is higher than 12 hours, the cooling and eruption of the high-temperature compacted iron become worse.
While an exemplary embodiment of the present invention has been described with reference to the accompanying drawing, those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other various forms without departing from the invention as claimed.
Accordingly, the aforementioned embodiment should not be construed as being limitative, but should be construed as being only illustrative from all aspects. The scope of the present invention is defined by the appended claims rather than the detailed description.
While this invention has been described in connection with what is presently considered to be a practical exemplary embodiment, it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

Claims

A method of manufacturing molten iron, comprising the steps of:
reducing fine iron ores into reduced fine iron by using a multi-stage fluidized furnace (100);

manufacturing high-temperature compacted iron by compressing the reduced fine iron using a compacted iron manufacturing device (200);

crushing the high-temperature compacted iron by using a crushing device (300);

conveying the crushed compacted iron to a charging device;

conveying some of the crushed compacted iron to a compacted iron storage tank (600);

distributing the crushed compacted iron to the charging device or the compacted iron storage tank (600) by using 2-direction chutes (700); and

charging the compacted iron from the charging device into a smelting furnace (500) and melting the charged compacted iron by combusting fine or lump coal,

wherein if the high-temperature compacted iron necessary for the smelting furnace (500) is able to be manufactured through the multi-stage fluidized furnace (100), the compacted iron manufacturing device (200), and the crushing device (300), excess high-temperature compacted iron exceeding an amount of the high-temperature compacted iron necessary for the smelting furnace (500) is manufactured, and the excess high-temperature compacted iron is intermittently conveyed to and stored in the compacted iron storage tank (600) by way of an action of the 2-direction chutes (700),

wherein if the high-temperature compacted iron necessary for the smelting furnace (500) is unable to be manufactured through the multi-stage fluidized furnace (100), the compacted iron manufacturing device (200), and the crushing device (300), the compacted iron stored in the compacted iron storage tank (600) is continuously supplied to the smelting furnace (500) via a conveyance device (450, 400),

wherein if a ratio of a yield of high-temperature compacted iron manufactured by the multi-stage fluidized furnace (100) the compacted iron manufacturing device (200), and the crushing device (300) and demand quantity of high-temperature compacted iron necessary for the smelting furnace (500) is defined by an excess rate as below,

the excess rate = (yield of the high-temperature compacted iron)/ (demand quantity of the high-temperature compacted iron) x 100,

the excess rate is 110% to 120%.
The method of claim 1, wherein a time that the high-temperature compacted iron stays in the compacted iron storage tank (600) is 6 hours to 12 hours.