CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to and the benefit of Korean Paten5 t
Application No. 10-2014-0173338 filed in the Korean Intellectual Property Office
on December 4, 2014, the entire contents of which are incorporated herein by
reference.
10 BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a system and a method for compacting
direct reduced iron.
(b) Description of the Related Art
15 Reduced direct iron is easily oxidized or has the risk of ignition due to
high reactivity when being exposed to air. The reactivity is caused by a
specific surface area of direct iron.
While the direct iron having a hematite form is reduced to magnetite, a
crystal structure is largely changed. Since lattice structures of the hematite
20 and the magnetite are very different from each other, the change causes
volume expansion and generates many internal cracks. The generation of the
cracks increases the specific surface area of ore and increases an area capable
of reacting with gas to finally contribute to the increase in reduction rate.
When the direct iron having a limonite form is heated at 500°C or more,
2
water from crystallization existing therein is discharged to the outside to be
changed into hematite. When the water from the crystallization is discharged,
a space occupied by the water from the crystallization is exposed outside, and
thus, the porosity and the specific surface area of ore are increased.
Since the reduced direct iron having hematite and limonite forms ha5 s
high reactivity due to the high specific surface area, the reduced direct iron
reacts with oxygen at room temperature which have a high possibility of being
ignited or reoxidized. For this reason, in order to reduce the reactivity of the
direct iron, a lot of effort such as coating or purging with nitrogen has been
10 made to reduce reactivity, but it is difficult to fundamentally block the possibility
of ignition during long-term storage or long-distance transportation.
Accordingly, in order to reduce the reactivity of the direct iron, it is
required to reduce the specific surface area, and accordingly, a technique for
compacting the direct ore has been developed. As the compacting technique,
15 a method of making (compacting) the direct reduced iron into a mass form by
plastic deformation through physical pressure has been frequently used.
FINMET, FINEX, or the like has a process of compacting the direct reduced iron.
The most efficient method (compacting) for making the direct iron into
the mass form is to supply and compress the direct reduced iron between two
20 rotating rollers, and thus, a throughput may be controlled according to the
number of revolution, that is, rpm of the roller. The compacting apparatus is
referred to as a roller compactor. A function of the roller compactor may be
defined as making direct iron having low density into a mass having high
density from the viewpoint of the particle and efficiently removing gas existing
3
between direct iron particles from the viewpoint of the gas.
When the gas existing between the direct iron particles is not efficiently
removed, gas existing between the particulate material is compressed when
engaging with the rollers, and thus, the pressure is increased and gas
compressed when passing through the rollers is expanded and thus, a compa5 ct
body may be broken. Further, when internal porosity of the particulate material
particles is high and force compressed by the rollers is removed, and thus, the
gas may be re-expanded. This is referred to as spring-back. The spring-back
phenomenon may be verified by a torque change of the rollers during the
10 operation. The torque of the roller may be expressed by multiplying a radius of
the roller by friction force applied between the roller and the molding body, and
when generating the spring-back, a phenomenon in which the molding body
slides with the roller occurs and thus, a torque value is lowered.
When the torque is decreased, the screw feeder more rapidly rotates to
15 supply more particulate material to the roller and thus, the torque is restored to
a predetermined value by increasing the friction force between the roller and the
molding body.
However, in the case of using ore having a lot of internal and external
pores, the porosity of the direct reduced iron is also increased, and as a result,
20 the rpm of the screw feeder is continuously at a maximum value. Alternatively,
when the direct reduced iron is not supplied to the screw feeder well, the screw
feeder may not supply the direct reduced iron to the roller, and thus, the torque
may not be increased. The roller compresses the direct reduced iron to
increase the density, but on the contrary, generate the gas. The generated
4
gas flows in an opposite direction to the direct reduced iron supplied by riding
the screw feeder. As a result, the supplied particulate material receives the
resistance and smooth supply is impossible. Therefore, in order to supply
more particulate material, the rpm of the screw feeder is naturally increased, but
substantially, the amount supplied to the roller is not increased5 .
As such, a torque value of the roller may be decreased by various
unstable factors which may be generated during operation, and the change in
torque of the roller may be more variously generated in the case of using
various apparatuses. A method of efficiently coping with the change in torque
10 is required.
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.
15 SUMMARY OF THE INVENTION
The present invention has been made in an effort to provide a system
and a method for compacting direct reduced iron having advantages of
suppressing a spring-back phenomenon and stabilizing an operation so that a
particulate material is smoothly supplied to a screw feeder by mixing a material
20 having low internal porosity and a dense structure.
An exemplary embodiment of the present invention provides a system
for compacting the direct reduced iron including: a first reservoir in which dense
iron oxide is stored; a second reservoir connected with the first reservoir to
receive the iron oxide; an iron oxide supply line of which one side is connected
5
with the first reservoir and the other side is connected with the second reservoir;
a reducing furnace connected with the second reservoir to provide the direct
reduced iron to the second reservoir; a direct reduced iron supply line of which
one side is connected with the reducing furnace and the other side is connected
with the second reservoir; a hot compacted iron (HCI) apparatus receiving an5 d
compacting a mixture of the iron oxide and the direct reduced iron which are
supplied to the second reservoir and mixed with each other through a screw
feeder; and a mixture supply line of which one side is connected with the
second reservoir and the other side is connected with the HCI apparatus.
10 The iron oxide may be slag, mill scale, iron sand, hematite, magnetite,
or a combination thereof.
The density of the iron oxide may be 4.5 to 8.0 g/cm3.
The specific surface areaof the iron oxide may be 0.05 to 10.0 m/cm3.
The D50 size of the iron oxide may be 0.05 to 5.0 mm.
15 The first reservoir may include a dryer for drying the iron oxide so that
the content of moisture in the iron oxide is more than 0 wt% and less than 3
wt%.
The dryer may be a fluidized bed dryer.
The first reservoir may further include a heater heating the iron oxide.
20 The reducing furnace may be a fluidized bed reducing furnace.
The reducing furnace may have a multi-step form.
When the iron oxide is maintained at room temperature, a mixing ratio of
the iron oxide in the mixture of the iron oxide and the direct reduced iron which
are supplied to the second reservoir and mixed with each other may be more
6
than 0 wt% and less than 25 wt%.
When the iron oxide is heated to 100 to 200°C, the mixing ratio of the
iron oxide in the mixture of the iron oxide and the direct reduced iron which are
supplied to the second reservoir and mixed with each other may be 25 to 40
wt%5 .
The HCI apparatus may be constituted by one or more HCI apparatuses.
The HCI apparatus may include a pair of rollers.
The HCI apparatus may be maintained in a temperature range of 500 to
800°C.
10 The system for compacting the direct reduced iron may further include a
first iron oxide supply line adding the dense iron oxide to the reducing furnace
by connecting the first reservoir and the reducing furnace.
The system for compacting the direct reduced iron may further include a
second iron oxide supply line adding the dense iron oxide to the reducing
15 furnaceby connecting the first reservoir and the mixture supply line.
Another exemplary embodiment of the present invention provides a
method for compacting direct reduced iron including: preparing dense iron
oxide; preparing direct reduced iron; mixing the iron oxide and the direct
reduced iron; and compacting the mixture.
20 In the preparing of the dense iron oxide, the iron oxide may be slag, mill
scale, iron sand, hematite, magnetite, or a combination thereof.
The density of the iron oxide may be 4.5 to 8.0 g/cm3.
The specific surface areaof the iron oxide may be 0.05 to 1.0 m/cm3.
The D50 size of the iron oxide may be 0.05 to 1.0 mm.
7
The preparing of the dense iron oxide may include drying and heating
the iron oxide.
The drying may be performed by a fluidized bed dryer and the content of
moisture in the iron oxide may be more than 0 wt% and less than 3 wt%.
In the mixing of the iron oxide and the direct reduced iron, when the iro5 n
oxide is maintained at room temperature, a mixing ratio of the iron oxide in the
mixture may be more than 0 wt% and less than 25 wt%.
In the mixing of the iron oxide and the direct reduced iron, when the iron
oxide is heated to 100 to 200°C, the mixing ratio of the iron oxide in the mixture
10 may be 25 to 40 wt%.
The preparing of the direct reduced iron may include adding the dense
iron oxide.
The compacting of the mixture may include adding the dense iron oxide
to the mixture.
15 According to the exemplary embodiment of the present invention, it is
possible to provide a system and a method for compacting direct reduced iron
capable of suppressing a spring-back phenomenon and stabilizing an operation
so that a particulate material is smoothly supplied to a screw feeder by mixing a
material having low internal porosity and a dense structure.
20 BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a system for compacting direct
reduced iron according to an exemplary embodiment of the present invention.
FIG. 2 is a schematic diagram of a compacting apparatus according to
another exemplary embodiment of the present invention.
8
FIG. 3 is a graph illustrating flowability of FINEX DRI.
FIG. 4 is a graph illustrating flowability when iron oxide is mixed.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Hereinafter, exemplary embodiments of the present invention will be
described in detail. However, the exemplary embodiments are proposed as a5 n
example, the present invention is not limited thereto, and the present invention
is defined by a range of claims to be described below.
Throughout the specification, unless explicitly described to the contrary,
the word “comprise” and variations such as “comprises” or “comprising”, will be
10 understood to imply the inclusion of stated elements but not the exclusion of
any other elements.
The drawings and description are to be regarded as illustrative in nature
and not restrictive. Like reference numerals designate like elements throughout
the specification.
15 Hereinafter, a configuration of a system for compacting direct reduced
iron according to an exemplary embodiment of the present invention will be
described in more detail with reference to the drawings.
FIG. 1 is a schematic diagram of a system for compacting direct
reduced iron according to an exemplary embodiment of the present invention.
20 The exemplary embodiment of the present invention provides a system
for compacting direct reduced iron including a first reservoir 10, a second
reservoir 20, an iron oxide supply line 11, a reducing furnace 30, a direct
reduced iron supply line 31, a hot compacted iron (HCI) apparatus 40, and
mixture supply lines 21a, 21b, and 21c.
9
In this case, an object of the system for compacting the direct reduced
iron is to supply a dense material to a screw feeder 41 of the HCI apparatus 40
and thus stabilize an operation by lowering a rotation rate of the screw feeder
41 through the above configuration.
First, the first reservoir 10 according to the exemplary embodiment o5 f
the present invention is a constitution element in which dense iron oxide is
stored.
In this specification, “dense” means that the apparent density of particles
is 4.5 to 8.0 g/cm3.
10 Further, in this specification, a “particle diameter" means a particle
diameter in the case where the particle has a spherical shape, and means an
average value obtained by measuring the diameters of multiple particles in a
predetermined direction when the particle has a complicated shape.
In this case, the iron oxide may be slag, mill scale, iron sand, hematite,
15 magnetite, or a combination thereof, but is not limited thereto.
The iron oxide has high density and relative low porosity, and is stored
in a fine structure form, and the density may be in a range of 4.5 to 8.0 g/cm3.
The density of pure iron (pure Fe) is 8.0 g/cm3, and when the density deviates
from the range, there is a problem in that the content of impurities may be rather
20 increased.
The specific surface area of iron oxide may be in a range of 0.05 to 10.0
m2/g, and more particularly, 0.05 to 1.0 m2/g. When the specific surface area
is more than 10.0 m2/g, it does not contribute at all to output deterioration and
stabilization of the screw feeder 41 of the HCI apparatus 40.
10
Further, a D50 size of the iron oxide may be in a range of 0.05 to 5.0
mm, and more particularly, 0.1 to 1.0 mm. When the D50 size of the iron oxide
is less than 0.05 mm, there is a problem in that elutriation in which the iron
oxide blows by gas discharged during compression is caused, and when the
D50 size of the iron oxide is more than 5.0 mm, the D50 size is larger than 5 a
distance between rollers as the component of the HCI apparatus 40, and thus it
may be a problem in compression molding.
Here, the D50 particle size (weight cumulative particle size) means a
particle size when iron oxide particles in which various particle sizes such as 0.1,
10 0.2, 0.3, …, 3, 5, 7, …, 10, 20, and 30 m are distributed are accumulated up to
a weight ratio of 50%.
Meanwhile, the first reservoir 10 according to the exemplary
embodiment of the present invention may include a dryer (not illustrated). In
this case, the dryer serves to dry the iron oxide so that the content of moisture
15 in the iron oxide is less than 3 wt%.
More particularly, the content of moisture in the iron oxide may be more
than 0 and less than 3 wt%. When the content of moisture in the iron oxide is
equal to or more than 3 wt%, cohesion between the iron oxide is increased and
thus, in the reservoir, a rat hole may be formed or a cohesive arch may be
20 formed.
For example, the dryer may be a fluidized bed dryer. Here, the
fluidized bed dryer means an apparatus of drying iron oxide particles while
moving like a fluid by blowing a hot wind below iron oxide charged on a porous
plate.
11
Further, the first reservoir 10 according to the exemplary embodiment of
the present invention may further include a heater (alternatively, a warmer) (not
illustrated).
The second reservoir 20 according to the exemplary embodiment of the
present invention is a component which is connected with the aforementione5 d
first reservoir 10 to receive the iron oxide.
In this case, the first reservoir 10 and the second reservoir 20 are
connected to each other by the iron oxide supply line 11.
The second reservoir 20 according to the exemplary embodiment of the
10 present invention serves to receive and mix the iron oxide and the direct
reduced iron from the reducing furnace 30 to be described below and then
supply the mixture to the HCI apparatus 40 to be described below.
In this case, when the iron oxide is maintained at room temperature, a
mixing ratio of the iron oxide in the mixture of the iron oxide and the direct
15 reduced iron may be more than 0 wt% and less than 25 wt%, and a method of
heating the iron oxide may be used so that the mixing ratio of the iron oxide in
the mixture is 25 wt% or more.
More particularly, when the iron oxide is heated to 100 to 200°C, the
mixing ratio of the iron oxide in the mixture of the iron oxide and the direct
20 reduced iron may be 25 to 40 wt%. This is a value which is arithmetically
calculated so that the temperature of the mixture is 500°C or more.
Here, the “room temperature” may be defined in a range of 20±5°C
according to the dictionaric meaning.
The reducing furnace 30 according to the exemplary embodiment of the
12
present invention is connected with the second reservoir 20 to provide the direct
reduced iron to the second reservoir 20.
In this case, the reducing furnace 30 and the second reservoir 20 are
connected to each other by the direct reduced iron supply line 31.
More particularly, the direct reduced iron is prepared with reducing ga5 s
or natural gas by gas combustion in the reducing furnace 30. In this case, the
reduction rate of the direct reduced iron may be in a range of 50 to 90%.
A particle size of direct ore which is reduced in the reducing furnace 30
to be the direct reduced iron is 8 mm or less, and the direct ore may be
10 hematite, limonite, or a combination thereof.
Further, the apparent density of the direct reduced iron may be 3.0 to
4.4 g/cm3. The apparent density is measured by using gas to become a
density value except for most of the pores formed outside. When considering
that the real density of pure hematite is 5.24, it may be predicted that closed
15 pores are high even though impurities are excluded. Further, the specific
surface area has a range of 10 to 90 m2/g. This means that opened pores also
are very high in the particulate materials.
When a lot of closed pores or/and opened pores exist, since the
possibility that spring-back occurs by the HCI apparatus 40 while compression
20 molding through the HCI apparatus 40 is increased and the density is lower
than the size of ore particles, the supply to the screw feeder 41 of the HCI
apparatus 40 may be suppressed by gas generated during compression
molding. As a result, the output of the screw feeder 41 may be increased by
the factors.
13
Further, according to a reduction condition in the reducing furnace 30,
the direct reduced iron may have various particle size distributions, densities,
pore rates, and the like, and when the particle size range is decreased and a lot
of fine particles are generated, the possibility that segregates are generated in
the second reservoir 20 is increased5 .
As a result, in the present invention, after the dense iron oxide described
above is supplied in the second reservoir 20 together with the direct reduced
iron, the iron oxide and the direct reduced iron are mixed to be supplied to the
screw feeder 41 of the HCI apparatus 40, thereby solving the problems.
10 In this case, the reducing furnace 30 according to the exemplary
embodiment of the present invention may be a fluidized bed reducing furnace,
and the fluidized bed reducing furnace may be constituted by a multi-step form.
When the reducing furnace 30 is constituted by the multi-step form, the
temperature range thereof may be 300 to 800°C for each reactor.
15 The HCI apparatus 40 according to the exemplary embodiment of the
present invention is constituted to receive and compact the mixture of the iron
oxide and the direct reduced iron which are supplied to the second reservoir 20
to be mixed with each other through the screw feeder 41.
In this case, the HCI apparatus 40 and the second reservoir 20 are
20 connected to each other by the mixture supply lines 21a, 21b, and 21c, and one
or more HCI apparatuses 40 may be constituted as illustrated in FIG. 1.
The HCI apparatus 40 may be constituted by one to five HCI
apparatuses. More particularly, the HCI apparatus 40 may be constituted by
one or three HCI apparatuses. This is a range which may be selected
14
depending on a target throughput.
FIG. 2 is a schematic diagram of the HCI apparatus according to the
exemplary embodiment of the present invention.
Referring to FIG. 2, the HCI apparatus 40 according to the exemplary
embodiment of the present invention may include a storage unit 42 in which th5 e
mixture may be stored, the screw feeder 41 in which the mixture stored in the
storage unit 42 is inserted, and a pair of rollers 43 pressing the mixture.
In the related art, when only the direct reduced iron is supplied to the
HCI apparatus 40 through the screw feeder 41, segregates may be generated
10 in the direct reduced iron of the second reservoir 20, and when the segregates
are generated, even though the direct reduced iron is equally supplied to a
plurality of HCI apparatuses 40, the screw feeders 41 of the HCI apparatuses
40 have different rotation rates.
The direct reduced iron is stored in the storage unit 42 and then
15 supplied to the rollers 43 by the screw feeder 41, and when rotational torque of
the rollers 43 deteriorates, the HCI apparatus 40 increases the supply amount
of the direct reduced iron stored in the storage unit 42 by increasing the number
of revolution of the screw feeder 41. As a result, when the number of
revolution of any one of the plurality of HCI apparatuses 40 becomes higher
20 than those of the other HCI apparatuses 40, the HCI apparatuses 40 reduce the
number of revolution of the screw feeder 41 by lowering the output. There is a
problem in that a difference in productivity for each HCI apparatus 40 is caused.
In order to solve the problem and increase the productivity by reducing
the rpm of the screw feeder 41, it is required to artificially add a material having
15
a high density and a small specific surface area, and in the present invention,
the effect may be obtained by mixing the dense iron oxide as the material.
In this case, the HCI apparatus 40 according to the exemplary
embodiment of the present invention may be constituted so that the
temperature of the mixture is uniformly maintained in a temperature range o5 f
500 to 800°C (a continuous type). In the case where the temperature of the
mixture is less than 500°C, when the HCI apparatus 40 is inserted to a melting
furnace, there are problems in that moldability deteriorates and the temperature
at the upper part of the melting furnace may be decreased. In the case where
10 the temperature of the mixture is more than 800°C, there is a problem in that a
thermal load is added to the HCI apparatus.
Meanwhile, the system for compacting the direct reduced iron according
to the exemplary embodiment of the present invention may further include a first
iron oxide supply line 111 adding the dense iron oxide to the reducing furnace
15 30 by connecting the first reservoir 10 and the reducing furnace 30, as
illustrated in FIG. 1.
Further, the system for compacting the direct reduced iron according to
the exemplary embodiment of the present invention may further include a
second iron oxide supply line 112 adding the dense iron oxide to the mixture
20 supply lines 21a, 21b, and 21c by connecting the first reservoir 10 and the
mixture supply lines 21a, 21b, and 21c, as illustrated in FIG. 1. When a
plurality of second reservoirs 20 is constituted and the numbers of rotation of
the screw feeders 41 of the plurality of HCI apparatuses 40 are high, the dense
iron oxide may be added along the second iron oxide supply line 112. In this
16
case, the temperature of the reducing furnace 30 is maintained to 700 to 800°C
to heat the iron oxide, and thus, the mixing ratio of the iron oxide may be 25
wt% or more. More particularly, the mixing ratio of the iron oxide may be 25 to
40 wt%. When the range is satisfied, the temperature of the mixture in the HCI
apparatus becomes 500°C or more, and thus, it is advantageous in molding5 .
Another exemplary embodiment of the present invention provides a
method for compacting direct reduced iron including: preparing dense iron oxide
(S10); preparing direct reduced iron (S20); mixing the iron oxide and the direct
reduced iron (S30); and compacting the mixture (S40).
10 More particularly, first, the dense iron oxide is prepared (S10).
In this case, the iron oxide may be slag, mill scale, iron sand, hematite,
magnetite, or a combination thereof, but is not limited thereto.
The iron oxide has high density and relatively low porosity, and is stored
in a fine structure form, and the density may be in a range of 4.5 to 8.0 g/cm3.
15 The specific surface area of iron oxide may be in a range of 0.05 to 10.0
m2/g, and more particularly, 0.05 to 1.0 m2/g.
Further, a D50 size of the iron oxide may be in a range of 0.05 to 5.0
mm, and more particularly, 0.1 to 1.0 mm.
Meanwhile, in another exemplary embodiment of the present invention,
20 the preparing of the dense iron oxide (S10) may include drying and heating the
iron oxide (S11).
In this case, the drying may be performed by a fluidized bed dryer, and
the content of moisture in the iron oxide becomes more than 0 wt% and less
than 3 wt%.
17
Further, in the case of performing the heating process, in the mixing of
the iron oxide and the direct reduced iron to be described below (S30), the
mixing ratio of the iron oxide in the mixture may be 25 wt% or more.
Thereafter, the direct reduced iron is prepared (S20).
In this case, in another exemplary embodiment of the present invention5 ,
the preparing of the direct reduced iron (S20) may include adding the dense
iron oxide (S21).
As described above, since the temperature of the reducing furnace is
maintained to 700 to 800°C to heat the iron oxide, if necessary, the mixing ratio
10 of the iron oxide is set to 25 wt% or more to stabilize the operation.
When the dense iron oxide and the direct reduced iron are prepared, the
iron oxide and the direct reduced iron are mixed (S30).
In this case, when the iron oxide is maintained at room temperature, a
mixing ratio of the iron oxide in the mixture may be more than 0 wt% and less
15 than 25 wt%, and a method of heating the iron oxide may be used so that the
mixing ratio of the iron oxide in the mixture is 25 wt% or more. In this case, the
heated temperature of the iron oxide may be 100 to 200°C.
When the iron oxide and the direct reduced iron are mixed, the mixture
is compacted (S40).
20 In this case, the compacting of the mixture (S40) may include adding the
dense iron oxide to the mixture (S41), and if necessary, the mixing ratio of the
iron oxide is set to 25 wt% or more to stabilize the operation.
Flowability of DRI may be represented like FIG. 3. Consolidation stress
means stress used to consolidate the particulate materials to a mass with the
18
consolidation stress, and unconfined yield stress means stress by which the
consolidated particulate materials mass is yielded when the consolidation stress
described above is removed. Since the stress required for the yield is
increased compared with the same consolidation stress as the slope is
increased, a particulate material having a large slope may be classified into no5 t
flowing, very cohesive, and cohesive, and a particulate material having a small
slope may be classified as easy flowing and free-flowing. The DRI in the
FINEX process is generally classified as the easy flowing. However, since the
flowability may vary according to a kind of used ore or iron oxide, it is required
10 to manage the flowability of the particulate material to be good, and more
progressively, when the easy-flowing particulate material may be improved to
the free-flowing particulate material, the fine DRI may be stably supplied
between the rollers.
Iron oxide of WRT has the density of 5.2 g/cm3, the specific surface area
of 0.058 m215 /g, and D50 of 0.30 nm. Even though the iron oxide is reduced, the
volume expansion degree is slight with the density of 5.1 g/cm3, the specific
surface area of 0.57 m2/g, and the D50 of 0.31 mm and the size thereof is
maintained. FIG. 4 illustrates a result of measuring flowability of the particulate
materials while increasing the mixing ratio of the reduced WRT in the FINEX
20 DRI to 5 wt% and 10 wt%, respectively. It can be seen that as the mixing ratio
of the reduced WRT is increased, the yield stress for the consolidation stress is
reduced and this indicates that the flowability is improved. The flowability is
improved by adding the iron oxide having the characteristic to reduce the output
of the screw and stabilize the operation.
19
While this invention has been described in connection with what is
presently considered to be practical exemplary embodiments, it is to be
understood that the invention is not limited to the disclosed embodiments, but,
on the contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended claims5 .
Therefore, it should be appreciated that the exemplary embodiments described
above are exemplificative in all aspects and not limitative.

10: First reservoir 11: Iron oxide supply line
10 111: First iron oxide supply line 112: Second iron oxide supply line
20: Second reservoir 21a, 21b, 21c: Mixture supply line
30: Reducing furnace 31: Direct reduced iron supply line
40: HCI apparatus 41: Screw feeder
42: Storage unit 43: Roller
15 While this invention has been described in connection with what is
presently considered to be practical exemplary embodiments, it is to be
understood that the invention is not limited to the disclosed embodiments, but,
on the contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended claims.

WHAT IS CLAIMED IS:
1. A system for compacting direct reduced iron, the system
comprising:
a first reservoir in which dense iron oxide is stored5 ;
a second reservoir connected with the first reservoir to receive the iron
oxide;
an iron oxide supply line of which one side is connected with the first
reservoir and the other side is connected with the second reservoir;
10 a reducing furnace connected with the second reservoir to provide the
direct reduced iron to the second reservoir;
a direct reduced iron supply line of which one side is connected with the
reducing furnace and the other side is connected with the second reservoir;
a hot compacted iron (HCI) apparatus receiving and compacting a
15 mixture of the iron oxide and the direct reduced iron which are supplied to the
second reservoir and mixed with each other through a screw feeder; and
a mixture supply line of which one side is connected with the second
reservoir and the other side is connected with the HCI apparatus.
20 2. The system of claim 1, wherein:
the iron oxide is slag, mill scale, iron sand, hematite, magnetite, or a
combination thereof.
3. The system of claim 2, wherein:
21
the density of the iron oxide is 4.5 to 8.0 g/cm3.
4. The system of claim 3, wherein:
the specific surface area of the iron oxide is 0.05 to 10.0 m2/g.
5
5. The system of claim 4, wherein:
the D50 size of the iron oxide is 0.05 to 5.0 mm.
6. The system of claim 1, wherein:
10 the first reservoir includes a dryer for drying the iron oxide so that the
content of moisture in the iron oxide is more than 0 wt% and less than 3 wt%.
7. The system of claim 6, wherein:
the dryer is a fluidized bed dryer.
15
8. The system of claim 6, wherein:
the first reservoir further includes a heater heating the iron oxide.
9. The system of claim 1, wherein:
20 he reducing furnace is a fluidized bed reducing furnace.
10. The system of claim 9, wherein:
he reducing furnace has a multi-step form.
22
11. The system of claim 1, wherein:
when the iron oxide is maintained at room temperature, a mixing ratio of
the iron oxide in the mixture of the iron oxide and the direct reduced iron which
are supplied to the second reservoir and mixed with each other is more than 0
wt% and less than 25 wt%5 .
12. The system of claim 8, wherein:
when the iron oxide is heated to 100 to 200°C, the mixing ratio of the
iron oxide in the mixture of the iron oxide and the direct reduced iron which are
10 supplied to the second reservoir and mixed with each other is 25 to 40 wt%.
13. The system of claim 1, wherein:
the HCI apparatus is constituted by one or more HCI apparatuses.
15 14. The system of claim 13, wherein:
the HCI apparatus includes a pair of rollers.
15. The system of claim 14, wherein:
the HCI apparatus is maintained in a temperature range of 500 to 800°C.
20
16. The system of claim 1, wherein:
a first iron oxide supply line adding the dense iron oxide to the reducing
furnace by connecting the first reservoir and the reducing furnace.
23
17. The system of claim 1, further comprising:
a second iron oxide supply line adding the dense iron oxide to the
mixture supply line by connecting the first reservoir and the mixture supply line.
18. A method for compacting direct reduced iron, the metho5 d
comprising:
preparing dense iron oxide;
preparing direct reduced iron;
mixing the iron oxide and the direct reduced iron; and
10 compacting the mixture;
DeletedTexts
19. The method of claim 18, wherein:
in the preparing of the dense iron oxide,
15 the iron oxide may be slag, mill scale, iron sand, hematite, magnetite, or
a combination thereof.
20. The method of claim 19, wherein:
the density of the iron oxide is 4.5 to 8.0 g/cm3.
20
21. The method of claim 20, wherein:
the specific surface area of the iron oxide is 0.05 to 1.0 m2/g.
22. The method of claim 21, wherein:
24
the D50 size of the iron oxide is 0.05 to 1.0 mm.
23. The method of claim 18, wherein:
the preparing of the dense iron oxide,
includes drying and heating the iron oxide5 .
24. The method of claim 23, wherein:
the drying is performed by a fluidized bed dryer and the content of
moisture in the iron oxide is more than 0 wt% and less than 3 wt%.
10
25. The method of claim 18, wherein:
in the mixing of the iron oxide and the direct reduced iron,
when the iron oxide is maintained at room temperature, a mixing ratio of
the iron oxide in the mixture is more than 0 wt% and less than 25 wt%.
15
26. The method of claim 23, wherein:
in the mixing of the iron oxide and the direct reduced iron,
when the iron oxide is heated to 100 to 200°C, the mixing ratio of the
iron oxide in the mixture is 25 to 40 wt%.
20
27. The method of claim 18, wherein:
the preparing of the direct reduced iron
includes adding the dense iron oxide.
25
28. The method of claim 18, wherein:
the compacting of the mixture,
includes adding the dense iron oxide to the mixture.