A METHOD AND APPARATUS FOR
MANUFACURING MOLTEN IRON
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an apparatus and method for manufacturing
molten Irons, and more particularly to an apparatus and method for manufacturing
molten irons that supplies oxygen and water to a fluidized-bed reactor for increasing a
temperature in the fluidized-bed reactor to thereby manufacture molten irons.
(b) Description of the Related 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 of the other products we use. It is also an industry with one of the longest
histories that has advanced together with human progress. In an iron foundry, which
plays a pivotal roll in the iron and steel industry, after molten iron (i.e., pig iron in a
molten state) is produced using iron ore and coal as raw materials, steel is produced
from the molten iron and is then supplied to customers.
Approximately 60% of the world's iron production is realized using the blast
furnace method developed in the 14th century. In the blast furnace method, cokes
produced using iron ore and bituminous coal that have undergone a sintering process
as raw materials are placed in a blast furnace, and oxygen is supplied to the furnace to
reduce the iron ore to iron to thereby manufacture molten iron. The blast furnace
method, which is a main aspect of molten iron production, requires raw materials
having a hardness of at least a predetermined level and grain size that can ensure
ventilation in the furnace. Coke in which specific raw coal that has undergone
processing is needed as a carbon source to be used as fuel and a reducing agent.
Also, sintered ore that has undergone a successive compacting process is needed as
an iron source. Accordingly, in the modern blast furnace method, it is necessary to
include raw material preparation and processing equipment such as coke
manufacturing equipment and sintering equipment. Therefore, not only is it necessary
to obtain accessory equipments in addition to the

blast furnace, but equipment to prevent and minimize the generation of pollution in
the accessory equipment is needed. The amount of investment, therefore, is
considerable, ultimately increases manufacturing costs.
In order to solve these problems of the blast furnace method, significant
effort is being put forth in iron foundries all over the world to develop a smelting
reduction process that produces molten irons by directly using fine coal as fuel and
as a reducing agent, and also directly using fine ores, which are used in over 80% of
the world's ore production, as an iron source.
As an example of such a smelting reduction process, U.S. Patent No.
5,584,910 discloses a method of manufacturing molten iron that directly uses fine
coals and fine ores. A method is disclosed in this patent for producing a molten pig
iron or molten steel preliminary product from a charge material that partially includes
fine iron ores. The fine iron ores are directly reduced into sponge irons in at least
one fluidized-bed reactor, and the sponge iron is melted in a melting region by
supplying carbon carriers and an oxygen containing gas. Reduced gas that is
generated in this process is provided to the fluidized-bed reactors, then is exhausted
as an exhaust gas after undergoing reaction.
When compared to the conventional blast furnace method, since the above
method for manufacturing molten iron uses fine iron ores and fine coals instead of
lump ores and cokes, the advantage is realized in which the range of grain sizes of
raw coal is wide. Further, equipment stoppages and re-starting are easy. However,
as a result of using the fine iron ores as raw material and also using multiple stages
of fluidized-bed reactors, it is not easy to adjust an inner state of the fluidized-bed
reactors, and in particular, an inner temperature thereof
Accordingly, in order to adjust an inner temperature of the fluidized-bed
reactors, a method is used in which a separate combustion chamber and burner are
provided to an exterior of the fluidized-bed reactors to thereby increase the
temperature of a gas supplied to the fluidized-bed reactors. However, when the
reaction gas that is increased in temperature passes through a dispersing plate
provided to induce uniform gas flow in the fluidized-bed reactors, ore particles
contained in the reaction gas fomn a compound having a low melting point such that
the dispersing plate becomes blocked, thereby making it impossible to perform
fluidized bed reduction process.
SUMMARY OF THE INVENTION
The present invention lias been made in an effort to solve the above
problems. The present invention provides an apparatus and method for
manufacturing molten iron that supplies oxygen and water directly to a fluidized-bed
reactor to increase a temperature of a reaction gas and prevent molten fine ores
from adhering to the fluidized-bed reactor thereby improving operation of the
fluidized-bed reactor.
The method for manufacturing molten iron includes the steps of producing
a mixture containing iron by drying and mixing iron ores and additives; passing the
mixture containing iron through one or more successively-connected fluidized beds
so that the mixture is reduced and calcined to thereby perform conversion into a
reduced material; forming a coal packed bed, which is a heat source in which the
reduced material has been melted; charging the reduced material to the coal packed
bed and supplying oxygen to the coal packed bed to manufacture molten irons; and
supplying reduced gas exhausted from the coal packed bed to the fluidized bed,
wherein in the step of converting the mixture to the reduced material, oxygen is
directly supplied and combusted in an area where reduced gas flows to the fluidized
bed.
In the step of converting the mixture containing iron to a reduced material,
water may be supplied separately from the oxygen supply combustion process and
then be mixed with the oxygen.
Preferably, the water is one of process water and steam. .
The water may be supplied at a rate of 300-500Nm^/hr.
Preferably, the oxygen is supplied and combusted in the case where an
internal temperature of a fluidized-bed reactor is 650°C or higher.
The step of converting the mixture containing iron to a reduced material
includes (a) pre-heating the mixture containing iron in a first fluidized bed; (b)
performing preliminary reduction of the pre-heated mixture containing iron in a
second fluidized bed; and (c) performing final reduction of the mixture containing
iron that has undergone preliminary reduction to thereby realize conversion into the
reduced material. The oxygen is directly supplied and combusted in the step (a) and
the step (b).
Oxygen may be supplied and combusted immediately prior to steps (a), (b).
and (c).
The apparatus for manufacturing molten iron includes one or more
fluidized-bed reactors that reduce and calcine iron ores and additives which are
dried and mixed to convert into a reduced material; a melter-gasifier for charging the
reduced material and receiving the supply of oxygen to manufacture molten irons;
and a reduced gas supply line for supplying reducing gas exhausted from the
melter-gasifier to the fluidized-bed reactors, wherein the fluidized-bed reactors each
include a dispersing plate at a lower area thereof and through which the reduced
gas passes, and an oxygen bumer mounted to an outer wall of the fluidized-bed
reactor at an area above the dispersing plate.
The oxygen bumer includes a first member inside of which coolant
circulates in a lengthwise direction; and a second member encompassed by the first
member along a lengthwise direction in a state separated from the same, and inside
of which coolant is circulated. Preferably, oxygen is supplied and combusted
between the first member and the second member, and a distance between the first
member and the second member is getting reduced as coming close to the inside of
fluidized-bed reactor.
The fluidized-bed reactors may each include a water supply nozzle
mounted to an outer wall of the fluidized-bed reactor at an area above the dispersing
plate, and positioned at an area in the vicinity of the oxygen burner.
A direction that the water supply nozzle supplies water is preferably at an
angle of 4~ 15° with respect to the lengthwise direction of the oxygen burner.
The water may be one of process water and steam.
The water may be atomized and supplied at a rate of 300-500Nm^/hr.
The fluidized-bed reactors may include a pre-heating furnace for pre-
heating the mixture containing iron; a preliminary reduction furnace connected to the
pre-heating furnace and performing preliminary reduction of the pre-heated mixture
containing iron; and a final reduction furnace connected to the preliminary reduction
furnace and performing final reduction of the mixture containing iron that has
undergone preliminary reduction to thereby realize conversion into the reduced
material, wherein an oxygen burner is included in each of the pre-heating furnace
and the preliminary reduction furnace.
Each of fluidized-bed reactors may further include a water supply nozzle
mounted to an outer wall of the fluidlzed-bed reactor at an area above the dispersing
plate, and positioned in the vicinity of the oxygen burner.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS " » »
FIG. 1 is a schematic view of an apparatus for manufacturing molten iron
according to a first embodiment of the present invention.
FIG. 2 is a partial sectional view of an oxygen burner according to a first
embodiment of the present invention.
FIG. 3 is a schematic view of an apparatus for manufacturing molten iron
according to a second embodiment of the present invention.
FIG. 4 is a partial sectional view of an oxygen burner and a water supply nozzle
according to a second embodiment of the present invention.
FIG. 5 is a graph showing changes in an oxygen flame temperature as a function
of water supply amount according to an experimental example of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will now be described in detail
with reference to the accompanying drawings. It should be clearly understood that
many variations and/or modifications of the basic inventive concepts may appear to
those skilled in the present art. The embodiments are to be regarded as illustrative in
nature, and not restrictive.
FIG. 1 is a schematic view of an apparatus for manufacturing molten iron
according to a first embodiment of the present invention. The apparatus is shown in a
state where oxygen burners are mounted to fluidized-bed reactors.
An apparatus 100 for manufacturing molten iron according to a first embodiment
of the present invenfion includes the main elements of a fluidized-bed reactor unit 20, a
melter-gasifier 10, and other accessory equipments. The fiuidized-bed reactor unit 20
includes one or more fluidized-bed reactors having a fluidized bed therein, and acts to
reduce and calcine iron ores and additives to reduced material. The reduced material is
charged to the melter-gasifier 10, which includes a coal packed bed therein, and
oxygen is supplied to the melter-gasifier 10 to thereby produce molten irons. Reduced
gas exhausted from the melter-gasifier 10 is used to reduce and calcine iron ores and
addifives by passing through the fiuidized-bed reactors after being supplied to the same
via a reduced gas supply line L55, after---------------------------------------------------------J
-5-
which the reduced gas is exhausted to the outside.
Elements included in the apparatus 100 for manufacturing molten iron
according to the first embodiment of the present invention will now be described in
more detail.
After temporarily storing fine ores containing iron and additives of a grain
size of 8mm or less at room temperature, the fluidized-bed reactor unit 20 removes
water from these elements in a drier 22 and mixes the same to produce a mixture
that contains iron. The mixture containing iron manufactured in this manner is
charged to the fluidized-bed reactors. An intermediate vessel 23 is provided
between the drier 22 and the fluidized-bed reactors such that the iron containing
mixture at room temperature is charged to the fluidized-bed reactors that are
maintained at a pressure from a normal pressure to 1.5—3.0 atmospheres.
As shown in FIG. 1, the fiuidized-bed reactors in the first embodiment of the
present invention are realized through three stages. This number of the fluidized-
bed reactors is for illustrative purposes only and is not meant to restrict the present
invention. Accordingly, a variety of different numbers of stages may be used for the
fluidized-bed reactors.
The fine ores containing iron and additives supplied to the fluidized-bed
reactors form a fluidized bed by contacting a high temperature reduced gas current,
and is converted into a high temperature reduced material that is at a temperature of
80°C or more, is 80% or more reduced, and is 30% or more calcined. As shown in
FIG. 1, in a first stage of the fluidized bed reduction process, the iron containing
mixture at room temperature is pre-heated in a pre-heating reactor 24. Next, in a
second stage, preliminary reduction of the pre-heated mixture containing iron is
performed in a preliminary reducing reactor 25, which is connected to the pre-
heating reactor 24. Finally, in a third stage, the iron containing mixtures that are
reduced in the preliminary reducing reactor 25 undergoes final reduction in a final
reducing reactor 26, which is connected to the preliminary reducing reactor 25.
Although not shown in FIG. 1, to prevent scattering loss when reduced
material exhausted from the fluidized-bed reactors is directly charged to the melter-
gasifier 10, a hot compacting apparatus may be mounted between these elements.
Further, a hot intermediate vessel 12 is provided for supplying the reduced material
exhausted from the fluidized-bed reactors to the melter-gasifier 10 to thereby make
supply of the reduced material to the melter-gasifier 10 easy.
Lump coal or shaped coal realized by compressing fine coal is supplied to
the melter-gasifier 10 to form a coal packed bed. The lump coal or shaped coal
supplied to the melter-gasifier 10 is gasified by a pyrolysis reaction at an upper area
of the coal-packed bed and by a combustion reaction using oxygen at a lower area
of the coal-packed bed. Hot reduced gas generated in the melter-gasifier 10 by the
gasified reaction is supplied in succession to the fluidized-bed reactors through the
reduced gas supply line L55, which is connected to a rear end of the final reducing
reactor 26, to be used as a reducing agent and fluidized gas.
A dome-shaped empty space is formed to an area above a coal packed
bed of the melter-gasifier 10. The flow rate of gas is reduced by the empty space
such that large amounts of fine ores included in the charged reduced material and
fine ores generated as a result of an abrupt increase in temperature of coal charged
in the melter-gasifier 10 are prevented from being discharged out of the melter-
gasifier 10. Further, such a configuration allows for absorbing of variations in
pressure in the melter-gasifier 10 caused by irregular changes in the amount of gas
generated as a result of directly using coal. The coal is gasified and removes volatile
matters while dropping to the bottom of the coal packed bed, and ultimately is
burned by oxygen supplied through tuyeres at the bottom of the melter-gasifier. The
generated combustion gas raises through the coal packed bed, and is converted
into high temperature reduced gas and exhausted to outside the melter-gasifier 10.
Part of the combusfion gas is scrubbed and cooled while passing through water
collecting devices 51 and 53 such that pressure applied to the melter-gasifier 10 is
maintained within the range of 3.0-3.5 atmospheres.
A cyclone 14 collects exhaust gas generated in the melter-gasifier 10 such
that dust is again supplied to the melter-gasifier 10, and gas is supplied as reduced
gas to the fluidized-bed reactors through the reduced gas supply line L55. Reduced
iron drops within the coal packed bed together with the coal to undergo final
reduction and smelting by combustion gas and combustion heat generated by
gasifying" and combusiting coal, after which the iron is exhausted to the outside.
Since reduced gas exhausted from the melter-gasifier 10 slowly decreases
in temperature while passing through the fluidized-bed reactors, additional oxygen
supply apparatuses 71, 72, and 73 are provided in the system. Oxygen is supplied
by the oxygen supply apparatuses 71, 72, and 73 to be partially combusted, and the
reduced gas is increased in temperature using the combustion heat while
maintaining a suitable level of oxidation of the reduced gas.
In the first embodiment of the present invention, in order to prevent reduced
gas raised in temperature from damaging or blocking a dispersing plate mounted to
a lower area of the fluidized-bed reactors and through which reduced gas passes,
oxygen is directly supplied to and combusted in an area where reduced gas flows to
fluidized beds of the fluidized-bed reactors. To realize this in the present invention,
as shown in the enlarged circle of FIG. 1, an oxygen bumer 60 is mounted to an
exterior wall of each of the fluidized-bed reactors at an area above a dispersing
plate 27. Therefore, the reduced gas is minimally increased in temperature by the
oxygen supplied through the oxygen supply apparatuses 71, 72, and 73. Also, it is
possible to further increase the temperature of the reduced gas by operation of the
oxygen bumers 60.
In the case where oxygen is supplied and combusted through the oxygen
burner 60 shown in the enlarged circle of FIG. 1, a combustion area 44 is formed in
the vicinity of the oxygen burner 60. In the first embodiment of the present invention,
oxygen is directly supplied to and combusted in the area where reduced gas flows to
the fluidized beds in the fluidized-bed reactors. Accordingly, with the formation of the
combustion area 44 in the area where the fluidized beds are formed where the
dispersing plate 27 is already passed, any negative affect given to the dispersing
plate 27 is minimized.
In the first embodiment of the present invention, one of the oxygen burners
60 is preferably mounted to the pre-heating reactor 24 and to the preliminary
reducing reactor 25 for direct supply and combustion of oxygen. Since a reduction
rate of the iron containing mixtures forming a fluidized layer is not very high in the
pre-heating reactor 24 and the preliminary reducing reactor 25, even if contact is
made with the oxygen flame, molten cohesion of the iron containing mixture is not
very significant. In contrast to this, material forming the fluidized beds reaches a
reduction rate of a predetermined level in the final reducing reactor 26 such that
there is concern for molten cohesion of the fine direct reduced iron such that oxygen
is preferably not directly supplied to the final reducing reactor 26.
In addition, in the case where an internal temperature of the pre-heating
8
reactor 24, the preliminary reducing reactor 25, and the final reducing reactor 26 (i.e.,
in the fluidized-bed reactors) is 650 °C or greater, it is preferable that oxygen is
supplied through the oxygen burners 60. If the oxygen burners 60 are operated to
supply oxygen when the internal temperature of the fluldized-bed reactors is less
than 6501;, part of the supplied oxygen is not burned and is instead mixed and
flows with the reduced gas to reduce the reduction rate of the iron containing
mixture. The oxygen burners 60 will be described in greater detail with reference to
FIG. 2.
FIG. 2 is a partial sectional view of one of the oxygen burners 60 according
to the first embodiment of the present invention. Since an exterior of the oxygen
burner 60 is easily understood by those skilled in the art, only a sectional view of this
element is shown.
As shown in FIG. 2, the oxygen burner 60 is formed in a double pipe
structure. The oxygen burner 60 includes a first member 601 inside of which coolant
circulates in a lengthwise direction, and a second member 611 encompassed by the
first member 601 along a lengthwise direction in a state separated from the same,
and inside of which coolant is circulated. The second member 611 includes a flame
sensor 616 provided to one end. The oxygen burner 60 may include additional
devices required for oxygen. Oxygen is supplied between the first member 601 and
the second member 611, and, as shown in FIG. 2, a distance between the first
member 601 and the second member 611 is getting reduced as coming close to the
inside of fluidized-bed reactor (i.e., in the direction of the arrows) such that oxygen is
combusted while being sprayed at a high pressure. Further, the oxygen is
concentrated toward a center position for supply and combustion such that the
oxygen is sprayed deep into the fiuidized bed in the fluidized-bed reactor while a
flame is effectively formed.
Cooling pipes 602 and 612 are formed respectively in the first member 601
and the second member 611 to protect the oxygen burner 60 from the high
temperature oxygen flame. A coolant is supplied and circulated through the cooling
pipes 602 and 612.
The flame sensor 616 mounted to one end of the second member 611
detects whether the oxygen supplied to within the fiuidized bed has been combusted.
The flame sensor 616 detects an oxygen flame within a matter of seconds during
reactor 24, the preliminary reducing reactor 25, and tiie final reducing reactor 26 (i.e.,
in the fluidized-bed reactors) is 650 °C or greater, it is preferable that oxygen is
supplied through the oxygen burners 60. If the oxygen burners 60 are operated to
supply oxygen when the internal temperature of the fluidized-bed reactors is less
than 6501;, part of the supplied oxygen is not burned and is instead mixed and
flows with the reduced gas to reduce the reduction rate of the iron containing
mixture. The oxygen burners 60 will be described in greater detail with reference to
FIG. 2.
FIG. 2 is a partial sectional view of one of the oxygen burners 60 according
to the first embodiment of the present invention. Since an exterior of the oxygen
burner 60 is easily understood by those skilled in the art, only a sectional view of this
element is shown.
As shown in FIG. 2, the oxygen burner 60 is formed in a double pipe
structure. The oxygen burner 60 includes a first member 601 inside of which coolant
circulates in a lengthwise direction, and a second member 611 encompassed by the
first member 601 along a lengthwise direction in a state separated from the same,
and inside of which coolant is circulated. The second member 611 includes a flame
sensor 616 provided to one end. The oxygen burner 60 may include additional
devices required for oxygen. Oxygen is supplied between the first member 601 and
the second member 611, and, as shown in FIG. 2, a distance between the first
member 601 and the second member 611 is getting reduced as coming close to the
inside of fluidized-bed reactor (i.e., in the direction of the arrows) such that oxygen is
combusted while being sprayed at a high pressure. Further, the oxygen is
concentrated toward a center position for supply and combustion such that the
oxygen is sprayed deep into the fluidized bed in the fluidized-bed reactor while a
flame is effectively formed.
Cooling pipes 602 and 612 are formed respectively in the first member 601
and the second member 611 to protect the oxygen burner 60 from the high
temperature oxygen flame. A coolant is supplied and circulated through the cooling
pipes 602 and 612.
The flame sensor 616 mounted to one end of the second member 611
detects whether the oxygen supplied to within the fluidized bed has been combusted.
The flame sensor 616 detects an oxygen flame within a matter of seconds during
oxygen supply, and continuously maintains tine oxygen flame. By the installed flame
sensor 616, there is no concern of a decrease in the reducing rate of the reducing
gas by oxygen not being combusted and mixed with the reducing gas, or of the
oxygen that is not combusted converting in one area and exploding.
A second embodiment of the present invention will be described below with
reference to FIGS. 3 and 4.
FIG. 3 is a schematic view of an apparatus for manufacturing molten iron
according to a second embodiment of the present invention. The apparatus is
shown in a state where oxygen burners and water supply nozzles are mounted to
fluidized-bed reactors.
An apparatus 200 for manufacturing molten iron according to a second
embodiment of the present invention is identical to the apparatus of the first
embodiment except for the water supply nozzles. Therefore, an explanation of these
identical elements will not be provided and the description will be concentrated on
the water supply nozzles.
As shown in the enlarged circle of FIG. 3, the apparatus 200 for
manufacturing molten iron according to the second embodiment of the present
invention includes a water supply nozzle 65 positioned in the vicinity of the oxygen
burners 60 mounted to the outer wall above the dispersing plate 27 in each of the
fluidized-bed reactors. The fluidized-bed reactors may include additional equipment
as needed.
The water supply nozzle 65 mixes and supplies water to the oxygen flame
supplied and formed through the oxygen burner 60 to thereby form a combustion
area 46. Accordingly, a temperature of the oxygen flame may be reduced such that
molten cohesion of reduced iron in a high temperature area by direct contact to the
oxygen flame or by the oxygen flame is minimized. In addition, by the reduction in
the temperature of the oxygen flame, damage to the material positioned opposite
where the oxygen flame is formed is decreased.
FIG. 4 is a partial sectional view of one of the oxygen burners and its
corresponding water supply nozzle according to the second embodiment of the
present invention. Since the oxygen burner 60 is identical to that of the first
embodiment of the present invention, a detailed description thereof is omitted. The
water supply nozzle 65 is structured including a pipe member 651 with an aperture

652 formed therein. Water is supplied through the aperture 652 separately from the
oxygen and mixed into the oxygen flame.
¦ In FIG. 4, although the water supply nozzle 65 is shown positioned directly
over the oxygen burner 60, such a configuration is shown merely to illustrate the
present invention and is not meant to limit the same. Accordingly, it is only
necessary that the water supply nozzle 65 be positioned in the vicinity of the oxygen
burner 60.
At least one of process water and steam used in the process to
manufacture molten iron may be individually or jointly mixed then used during
oxygen supply and combustion. In this case, the temperature of the oxygen flame is
not only reduced, but as a result of water shift reaction resulting from an oxygen
flame of a maximum temperature, the supplied process water or steam is separated
into its elements of oxygen and hydrogen. The oxygen is combusted in the oxygen
flame, and the hydrogen is included in the reduced gas to aid in the reduction
reaction of the iron containing mixture. In particular, hydrogen is mainly used as a
reducing agent in methods to manufacture molten iron, and is a powerful reducing
agent that has approximately four times the reducing strength of carbon monoxide.
Therefore, water supply is highly preferable.
Water atomized and supplied through the water supply nozzle 65 is
preferably supplied at a rate of 300~500Nm^/hr. If water is not atomized and
supplied, and instead directly supplied, a water shift reaction or a cooling effect of
combustion gas is unable to be obtained.
If the supply rate of water is less than 300Nm%r, the oxygen flame
temperature is unable to be reduced. Further, the amount of resolved oxygen and
hydrogen is small such that the water supply effect is minimal and the oxygen
supply flow rate of the oxygen burner 60 is low, thereby possibly causing
malfunction of the oxygen burner 60. If the amount of water supplied exceeds
500Nm^/hr, an amount of water of more than needed contacts the oxygen flame to
reduce the heating effect of the fluidized beds by the oxygen flame by half. In
addition, water that does not participate in the water shift reaction and is left
remaining in a steam state acts as a binder to thereby possibly cause cohesion of
the iron containing mixture.
In the second embodiment of the present invention, the water supply nozzle

65 is mounted such that a direction along which it supplies water is set at an angle
(9) of 4-15° with respect to a lengthwise direction of the oxygen burner 60. As
shown in FIG. 4, in the case where the water supply nozzle 65 is provided above the
oxygen burner 60, it is preferable that the water supply nozzle 65 is slanted
downwardly 4 — 15° .If the angle (9) is less than 4° , the point at which contact is
made to the oxygen flame is further extended into the fluidized bed or does not
contact the oxygen flame at all. If the angle {9) exceeds 15° , not only is the supply
path of the oxygen flame obstructed, but the amount of time to reach the oxygen
flame is too short such that a reduction in temperature of the oxygen flame and the
water shift reaction cannot be expected.
The present invention will be described in greater detail below through an
experimental example. This experimental example merely illustrates the present
invention and is not meant to limit the present invention.
Experimental Example
At the same time oxygen is supplied through the oxygen burner, water is
supplied through the water supply nozzle to adjust the water supply amount
according to the second embodiment of the present invention. A simulating
experiment was performed to measure the resulting oxygen flame temperature. The
water supply amount is measured using a flow meter, and the oxygen flame
temperature is measured using a UV thermometer.
The test results are shown in FIG. 5. FIG. 5 is a graph showing changes in
an oxygen flame temperature as a function of water supply amount according to the
experimental example of the present invention. In the experimental example of the
present invention, an atmospheric temperature is set at 600 °C or greater such that
an oxygen flame is generated, but since this is a test with respect to an oxygen
flame in atmosphere, there may be a difference in the absolute temperature value.
However, the reduction in temperature may be predicted as shown in the graph of
FIG. 5.
As shown in FIG. 5, in the case where water is supplied to inside the
oxygen flame at a rate of approximately 300Nm^/hr, the temperature of oxygen
flame was reduced from about 27001; to about 2000°C. The amount of oxygen and
the amount of hydrogen generated in this case were each approximately 300Nm^/hr.
Also, in the case where water is supplied to inside the oxygen flame at a rate of

approximately 500Nm'/hr, the oxygen flame was reduced from about 2700 °C to
about 1500t;. The amount of oxygen and the amount of hydrogen generated in this
case were each approximately 500Nm%r.
In analyzing the relation between oxygen flame temperature to the water
supply amount in this Experimental Example, it is clear that for every 1Nm^/hr of
water that is supplied, the temperature of the oxygen flame is reduced by
approximately 2.531;.
Since in the present invention oxygen is directly supplied to an area where
reduced gas flows to fluidized beds, not only is the negative impact given to the
dispersing plate minimized, but the rate of reduction of the iron containing mixture is
increased by increasing the temperature of the reduction gas. Therefore, the quality
of reduced gas passing through the fluidized beds may be improved and cohesion of
the iron containing powder may be prevented.
Also, water is supplied separately from the oxygen supply combustion such
that the temperature of reduced gas is reduced. Hence, damage to contents
opposite the area where oxygen is supplied is prevented and the reduction ability of
the reducing gas is enhanced.
With respect to the water supply nozzle of the present invention, since
there is used process water or steam that enables the process in the manufacture of
molten iron to be easily realized, these processes may be more efficiently performed.
Further, in the present invention, in addition to performing the direct supply
of and combustion of oxygen in the fluidized beds, a separate oxygen supply
apparatus is provided outside the fluidized beds such that the load with respect to
oxygen supply may be lessened.
Although embodiments of the present invention have been described in
detail hei-einabove in connection with certain exemplary embodiments, it should be
understood that the invention is not limited to the disclosed exemplary embodiments,
but, on the contrary is intended to cover various modifications and/or equivalent
arrangements included within the spirit and scope of the present invention, as
defined in the appended claims.
WE CLAIM :
1. A method for manufacturing molten iron, comprising the steps of:
producing a mixture containing iron by drying and mixing iron containing ores
and additives;
passing the mixture containing iron through one or more successively-connected
fluidized beds so that the mixture is reduced and calcined to thereby perform
conversion into a reduced material;
forming a coal packed bed, which is a heat source in which the reduced material
has been melted;
charging the reduced material to the coal packed bed and supplying oxygen to
the coal packed bed to manufacture iron; and
supplying reduced gas exhausted from the coal packed bed to the fluidized bed,
wherein in the step of converting the mixture to a reduced material, oxygen is
directly supplied and combusted in an area where reduced gas flows to the fluidized
bed.
2. The method as claimed in claim 1, wherein in the step of converting the
mixture containing iron to a reduced material, water is supplied separately from oxygen
supply combustion process and is mixed with the oxygen.
3. The method as claimed in claim 2, wherein the water is one of process water and
steam.
4. The method as claimed in claim 2, wherein the water is supplied at a rate of 300-
500Nm3/hr.
5. The method as claimed in claim 1, wherein the oxygen is supplied and combusted in
the case where an internal temperature of a fluidized-bed is 650: or higher.

6. The method as claimed in claim 1, wherein the step of converting the mixture
containing iron to a reduced material comprises the steps of:

(a) pre-heating the mixture containing iron in a first fluidized bed;
(b) performing preliminary reduction of the pre-heated mixture containing iron in
a second fluidized bed; and
(c) performing final reduction of the mixture containing iron that has undergone
preliminary reduction to thereby realize conversion into the reduced material,
wherein the oxygen is directly supplied and combusted in the steps of (a) and
(b).
7. The method as claimed in claim 6, wherein oxygen is supplied and combusted
immediately prior to steps (a), (b), and (c).
8. The method as claimed in claim 7, wherein water is supplied separately from
the supply and combustion of the oxygen.
9. An apparatus for manufacturing molten iron (100), comprising:
one or more fluidized-bed reactors (24, 25, 26) that reduce and calcine iron ores
and additives which are dried and mixed, to convert into a reduced material;
a melter-gasifier (10) for charging the reduced material and receiving the supply
of oxygen to manufacture iron; and
a reduced gas supply line (L55) for supplying reducing gas exhausted from the
melter-gasifier (10) to the fluidized-bed reactors (24, 25, 26),
wherein the fluidized-bed reactors (24, 25, 26) each include a dispersing plate
(27) at a lower area thereof and through which the reduced gas passes, and an oxygen
burner (60) mounted to an outer wall of the fluidized-bed reactors (24, 25, 26) at an
area above the dispersing plate (27).
10. The apparatus as claimed in claim 9, wherein the oxygen burner (60)
comprises:
a first member (601) inside of which coolant circulates in a lengthwise direction;
and

a second member (611) encompassed by the first member (601) along a
lengthwise direction in a state separated from the same, and inside of which coolant is
circulated,
wherein oxygen is supplied and combusted between the first member (601) and
the second member (611), and a distance between the first member (601) and the
second member (611) is getting reduced as coming close to the inside of the fluidized-
bed reactors (24, 25, 26).
11. The apparatus as claimed in claim 9, wherein each of the fluidized-bed
reactors (24, 25, 26) is provided with a water supply nozzle (65) mounted to an outer
wall of the fluidized-bed reactors (24, 25, 26) at an area above the dispersing plate
(27), and positioned at an area in the vicinity of the oxygen burner (60).
12. The apparatus as claimed in claim 11, wherein a direction that the water
supply nozzle (65) supplies water is at an angle of 4-15° with respect to the lengthwise
direction of the oxygen burner (60).
13. The apparatus as claimed in claim 12, wherein the water is one of process
water and steam.
14. The apparatus as claimed in claim 12, wherein the water is atomized and
supplied at a rate of 300-500Nm3/hr.
15. The apparatus as claimed in claim 9, wherein each of the fluidized-bed
reactors (24, 25, 26) comprises:
a pre-heating furnace (24) for pre-heating the mixture containing iron;
a preliminary reduction furnace (25) connected to the pre-heating furnace (24)
and performing preliminary reduction of the pre-heated mixture containing iron; and
a final reduction furnace (26) connected to the preliminary reduction furnace (25)
and performing final reduction of the mixture containing iron that has undergone
preliminary reduction to thereby realize conversion into the reduced material,

wherein an oxygen burner (60) is included in each of the pre-heating furnace
(24) and the preliminary reduction furnace (25).
16. The apparatus as claimed in claim 15, wherein each of the fluidized-bed
reactors (24, 25, 26) further comprises a water supply nozzle (65) mounted to an outer
wall of the fluidized-bed reactors (24, 25, 26) at an area above the dispersing plate
(27), and is positioned in the vicinity of the oxygen burner (60).

The present invention relates to an apparatus (100) and method for
manufacturing molten iron to supply oxygen and water directly to a fluidized-bed
reactors (24, 25, 26) to increase a temperature of a reaction gas and prevent molten
fine ores from adhering to the fluidized-bed reactors (24, 25, 26) thereby improving
operation of the fluidized-bed reactors (24, 25, 26). The method for manufacturing
molten iron includes producing a mixture containing iron by drying and mixing iron-
containing ore and additives; passing the mixture containing iron through one or more
successively-connected fluidized beds so that the mixture is reduced and calcined to
thereby perform conversion into a reduced material; forming a coal packed bed, which
is a heat source in which the reduced material has been melted; charging the reduced
material to the coal packed bed and supplying oxygen to the coal-packed bed to
manufacture iron; and supplying reduced gas exhausted from the coal-packed bed to
the fluidized bed, wherein in the conversion of the mixture to a reduced material,
oxygen is directly supplied and combusted in an area where reduced gas flows to the
fluidized bed.