Technical Field
[0001] The present invention relates to a method for manufacturing sintered ore including
controlling the amounts of, for example, CaO-containing raw materials added in a sintering
raw material, and in particular, to a method for manufacturing sintered ore including
continuously measuring component concentrations in the sintering raw material and
controlling the amount of, for example, CaO-containing raw materials added in accordance
with the measured component concentrations.
Background Art
[0002] In blast furnace ironmaking methods, nowadays, sintered ore, lump iron ore, pellets,
and so forth are mainly used as iron sources for blast furnace feed materials. Here,
sintered ore is a kind of agglomerated ore manufactured in such a manner that iron
ore having a particle size of 10 mm or less, miscellaneous iron sources, such as various
kinds of dust generated in a steel plant, CaO-containing raw materials, such as limestone,
quick lime, and slag, auxiliary materials serving as SiO
2 sources or MgO sources, such as silica stone, serpentinite, dolomite, and nickel
refining slag, and solid fuels (carbonaceous materials) serving as bonding agents,
such as coke breeze and anthracite, are mixed and granulated in a drum mixer while
water is added, and then burned.
[0003] In recent years, the concentration of iron in iron ore contained in a sintering raw
material, which is a raw material for sintered ore, has been decreasing, and, instead,
the concentrations of gangue components, such as SiO
2 and Al
2O
3, have been increasing. In addition, the component concentrations in iron ore produced
have become variable to such an extent that, even in the case of the same kind of
iron ore, the component concentrations may vary from one ship to another when the
iron ore is imported. Also, in the case of various kinds of dust generated in a steel
plant, since there is a large variation in the amounts of the dust generated and in
the component concentrations in the dust, it is very difficult to control the components
of a sintering raw material.
[0004] A variation in the component concentrations in a sintering raw material causes a
variation in the component concentrations in sintered ore, which is a product. For
example, an increase in the amount of SiO
2 generally causes a deterioration in the reducibility of sintered ore, and an increase
in the amount of Al
2O
3 generally causes a decrease in the strength of sintered ore. Therefore, in the case
where the component concentrations in a sintering raw material deviate from target
values, it is necessary to perform operational adjustment and composition adjustment
to avoid a deterioration in product quality.
[0005] Generally, the component concentrations in sintered ore which is charged into a blast
furnace are constantly controlled for the purpose of, for example, controlling the
quality of slag. For example, in the case where, regarding the components of product
sintered ore, there is an increase in the basicity or the alumina content, since there
is an increase in the viscosity of blast furnace slag, it is necessary to increase
the temperature of molten iron to inhibit an increase in viscosity. Due to an increase
in the viscosity of blast furnace slag, since there is a deterioration in the slag-discharging
efficiency in the lower part of a blast furnace, gas flow is inhibited, which results
in a deterioration in gas permeability. Therefore, it is necessary to increase the
amount of coke added to increase the temperature of molten iron and to achieve satisfactory
gas permeability in the lower part of a blast furnace. Like this, in the case where
there is a variation in the component concentrations in product sintered ore such
that the component concentrations in blast furnace feed materials significantly deviate
from target component concentrations, the operation of a blast furnace becomes unstable.
Therefore, various countermeasures are necessary.
[0006] In response to such problems, various efforts have been made to estimate the quality
of a sintering raw material. For example, Patent Literature 1 discloses a technique
focusing on clay minerals contained in iron ore in which the granulation capability
of a sintering raw material is improved by controlling the content of a clay mineral
(kaolin: Al
2Si
2O
5(OH)
4) in finely powdered ore contained in iron ore to be within an appropriate range.
[0007] Patent Literature 2 discloses a technique in which the FeO concentration in product
sintered ore is measured and in which the bonding agents and granulation water content
for a sintering raw material and an air-discharging rate are adjusted in accordance
with the FeO concentration in the product sintered ore. Also, Patent Literature 3
discloses a technique in which the FeO concentration in product sintered ore is measured
and in which the amount of city gas injected into a sintering machine is adjusted
in accordance with the FeO concentration in the product sintered ore.
[0008] Patent Literature 4 discloses a technique in which the component concentrations
in product sintered ore are estimated on the basis of the component concentrations
in a surface layer of the burden layer of a sintering raw material, which has been
charged onto a pallet, and determined by using a laser-type component measuring device
disposed above a sintering machine and in which the composition of a sintering raw
material is adjusted in accordance with the estimation results.
Citation List
Patent Literature
[0009]
PTL 1: Japanese Unexamined Patent Application Publication No. 2003-049227
PTL 2: Japanese Unexamined Patent Application Publication No. 57-149433
PTL 3: Japanese Unexamined Patent Application Publication No. 2011-038735
PTL 4: Japanese Unexamined Patent Application Publication No. 60-262926
Summary of Invention
Technical Problem
[0010] In the case of the technique disclosed in Patent Literature 1, a certain amount of
iron ore sample is weighed out, and the kaolin concentration is determined offline.
Although it is possible to estimate the component concentrations in sintered ore by
measuring the component concentrations in a sintering raw material offline as described
above, it is difficult to address the heat quantity excess or deficiency caused by
a variation in the component concentrations in a sintering raw material during manufacture
of sintering ore.
[0011] In the case of the techniques disclosed in Patent Literature 2 and Patent Literature
3, although the FeO concentration in product sintered ore is continuously determined,
since the time lag is too large to reflect the results of the component analysis of
the product sintered ore in the composition adjustment of a sintering raw material,
it is difficult to rapidly address a variation in the component concentrations in
the sintering raw material during manufacture of sintered ore.
[0012] In the case of the technique disclosed in Patent Literature 4, although the component
concentrations in product sintered ore are estimated on the basis of the component
concentrations in the surface layer of a burden layer of a sintering raw material,
since there is a variation in the conditions of the burden layer of the sintering
raw material in accordance with a charging apparatus for the sintering raw material
and the water content of the sintering raw material, there is a variation in the component
concentrations in the surface layer of the burden layer of the sintering raw material.
Therefore, there is no definite relationship between the component concentrations
in the surface layer of the burden layer and the component concentrations in the product
sintered ore, which makes it difficult to practically estimate the component concentrations
in the product sintered ore on the basis of the component concentrations in the surface
layer of the burden layer.
[0013] The present invention has been completed in view of such problems of the conventional
techniques, and an object of the present invention is to provide a method for manufacturing
sintered ore with which, even in the case where there is a variation in the component
concentrations in iron ore and dust generated in a steel plant, it is possible to
manufacture product sintered ore with only a small variation in component concentrations
by using a sintering raw material containing such iron ore and dust.
Solution to Problem
[0014] The features of the present invention for solving such problems are as follows.
- (1) A method for manufacturing sintered ore, in which a sintering raw material containing
at least an iron-containing raw material, a CaO-containing raw material, and a bonding
agent is granulated, and the granulated sintering raw material is sintered in a sintering
machine, the method including a measuring process of continuously measuring a component
concentration in at least one of the iron-containing raw material, the sintering raw
material, and the granulated sintering raw material, and an adjusting process of adjusting
at least one of an amount of the CaO-containing raw material added, an amount of the
bonding agent added, an amount of water added, and a moving speed of a pallet carriage
of the sintering machine in accordance with the component concentration measured in
the measuring process.
- (2) The method for manufacturing sintered ore according to item (1), in which the
sintering raw material further contains a MgO-containing raw material and in which
at least one of the amount of the CaO-containing raw material added, an amount of
the MgO-containing raw material added, the amount of the bonding agent added, the
amount of the water added, and the moving speed of the pallet carriage of the sintering
machine is adjusted in the adjusting process in accordance with the component concentration
measured in the measuring process.
- (3) A method for manufacturing sintered ore, in which a sintering raw material containing
at least an iron-containing raw material, a CaO-containing raw material, and a bonding
agent is granulated, and the granulated sintering raw material is sintered in a sintering
machine while a gas fuel and oxygen are fed, the method including a measuring process
of continuously measuring a component concentration in at least one of the iron-containing
raw material, the sintering raw material, and the granulated sintering raw material,
and an adjusting process of adjusting at least one of an amount of the CaO-containing
raw material added, an amount of the bonding agent added, an amount of water added,
a moving speed of a pallet carriage of the sintering machine, an amount of the gas
fuel fed, and an amount of the oxygen fed in accordance with the component concentration
measured in the measuring process.
- (4) The method for manufacturing sintered ore according to item (3), in which the
sintering raw material further contains a MgO-containing raw material and in which
at least one of the amount of the CaO-containing raw material added, an amount of
the MgO-containing raw material added, the amount of the bonding agent added, the
amount of the water added, the moving speed of the pallet carriage of the sintering
machine, the amount of the gas fuel fed, and the amount of the oxygen fed is adjusted
in the adjusting process in accordance with the component concentration measured in
the measuring process.
- (5) The method for manufacturing sintered ore according to any one of items (1) to
(4), in which a concentration of at least one of total-CaO, SiO2, MgO, Al2O3, FeO, C, and water is measured in the measuring process.
Advantageous Effects of Invention
[0015] By implementing the method for manufacturing sintered ore according to the present
invention, it is possible to manufacture product sintered ore in which there is only
a small variation in component concentrations and in which a deterioration in quality
is inhibited by using a sintering raw material containing iron ore and dust generated
in a steel plant in which there is a large variation in component concentrations.
Brief Description of Drawings
[0016]
Fig. 1 is a schematic diagram illustrating an example of sintered ore manufacturing
equipment 10 with which the method for manufacturing sintered ore according to the
present embodiment is implemented.
Fig. 2 includes graphs illustrating the variations of the basicity of a sintering
raw material and the drop strength of product sintered ore 72 in the case of example
1 of the present invention.
Fig. 3 includes graphs illustrating the variations of the basicity of a sintering
raw material and the drop strength of product sintered ore 72 in the case of comparative
example 1.
Fig. 4 includes graphs illustrating the variations of the production rate of the sintering
machine, the carbon concentration in a sintering raw material, and the moving speed
of a pallet carriage in the case of example 2 of the present invention.
Fig. 5 includes graphs illustrating the variations of the production rate of the sintering
machine, the carbon concentration in a sintering raw material, and the moving speed
of a pallet carriage in the case of comparative example 2.
Description of Embodiments
[0017] Hereafter, the present invention will be described in accordance with the embodiment
of the present invention. Fig. 1 is a schematic diagram illustrating an example of
sintered ore manufacturing equipment 10 with which the method for manufacturing sintered
ore according to the present embodiment is implemented. An iron-containing raw material
12 which is stored in a yard 11 is transported to a blending tank 22 via a transporting
conveyer 14. The iron-containing raw material 12 contains various brands of iron ore
and dust generated in a steel plant.
[0018] A raw material feeding apparatus 20 has plural blending tanks 22, 24, 25, 26, and
28. The blending tank 22 contains the iron-containing raw material 12. The blending
tank 24 contains a CaO-containing raw material 16 including limestone, quicklime,
and so forth. The blending tank 25 contains a MgO-containing raw material 17 including
dolomite, nickel refining slag, and so forth. The blending tank 26 contains a bonding
agent 18 including coke breeze, which is prepared by crushing in a rod mill so that
the particle diameter is 1 mm or less, and anthracite. The blending tank 28 contains
return ore having a particle diameter of 5 mm or less, which is the portion of sintered
ore passing through sieves for sintered ore (powder under the sieves for sintered
ore). Predetermined amounts of the raw materials are discharged from each of the blending
tanks 22 through 28 of the raw material feeding apparatus 20, and a mixture of the
discharged raw materials is used as a sintering raw material. The sintering raw material
is transported to a drum mixer 36 via a transporting conveyer 30. Since the MgO-containing
raw material 17 is an optional blending material, it may be contained or not in the
sintering raw material.
[0019] In a transporting conveyer 30 placed between the blending tank 28 and the drum mixer
36, an infrared analyzer 32 is installed. By using the infrared analyzer 32, a measuring
process is performed. In the measuring process, the concentration of at least one
of total-CaO, SiO
2, MgO, Al
2O
3, FeO, C, and water which are contained in the sintering raw material is measured.
Here, the term "water" refers to a combination of adhered water, which adheres to
the sintering raw material, and inherent water, which is held within the raw materials
at constant temperature and removed from the raw materials by heating.
[0020] The infrared analyzer 32 radiates infrared light having a wavelength of 0.5 µm to
50.0 µm onto the sintering raw material and receives reflected light from the sintering
raw material. Since total-CaO, SiO
2, MgO, Al
2O
3, FeO, and water which are contained in the sintering raw material each have respective
molecular vibrations and each absorb respective specific-wavelength components of
the radiated infrared light, these components each impart respective specific-wavelength
components to the reflected infrared light. Also, the crystal structure of a single-atom
molecule, such as carbon (C), starts to vibrate at the time of radiating the infrared
light and thereby imparts the specific-wavelength component to the reflected infrared
light. Therefore, it is possible to determine the concentrations of total-CaO, SiO
2, MgO, Al
2O
3, FeO, C, and water in the sintering raw material by analyzing the radiated infrared
light and the reflected infrared light. The term "total-CaO" refers to the total amount
of Ca in terms of CaO in all the compounds including Ca and O, such as CaO, CaCO
3, Ca(OH)
2, and Fe
2CaO
4.
[0021] For example, the infrared analyzer 32 radiates infrared light having 20 or more wavelengths
and receives reflected light reflected from the sintering raw material at a frequency
of 128 times per minute. Since it is possible to radiate infrared light in such a
short time by using the infrared analyzer 32, it is possible to continuously measure
the component concentrations in the sintering raw material, which is transported on
the transporting conveyer 30, online by using the infrared analyzer 32. Since the
infrared analyzer 32 is an example of an analyzing device which is used to measure
the component concentrations in the sintering raw material, a laser analyzer which
radiates laser beams onto an object to be measured, a neutron analyzer which radiates
neutrons onto an object to be measured, or a microwave analyzer which radiates microwaves
onto an object to be measured may be used instead of the infrared analyzer 32.
[0022] The sintering raw material, which has been transported to the drum mixer 36, is charged
into the drum mixer 36 with an appropriate amount of water 34 being added and granulated
to form quasi-particles having an average particle diameter of, for example, 3.0 mm
to 6.0 mm. The granulated sintering raw material is transported via a transporting
conveyer 38 to a sintering raw material feeder of a sintering machine 40. Since the
drum mixer 36 is an example of a granulating apparatus which is used to granulate
the sintering raw material, plural drum mixers 36 may be used, and a pelletizer may
be used as a granulating apparatus instead of the drum mixer 36. Both the drum mixer
36 and the pelletizer may be used, and a high-speed stirring apparatus may be placed
upstream of the drum mixer 36 to stir the sintering raw material. In the present embodiment,
the term "average particle diameter" refers to an arithmetic average particle diameter
defined by the formula ∑(Vi × di), where Vi denotes the abundance ratio of particles
having a particle diameter within the i-th range defined in terms of particle diameter
and di denotes the representative particle diameter of the i-th range).
[0023] An adjusting process is performed in such a manner that at least one of the amount
of the CaO-containing raw material 16 added, the amount of the bonding agent 18 added,
and the amount of water 34 added in the drum mixer 36 is adjusted in accordance with
the component concentrations in the sintering raw material measured in the measuring
process so that a predetermined target value is achieved. The meaning of the term
"predetermined target value" includes, for example, the basicity (CaO/SiO
2) of the sintering raw material, the carbon concentration in the sintering raw material,
the MgO concentration in the sintering raw material, the water concentration in the
sintering raw material, the Al
2O
3 concentration in the sintering raw material, and the heat quantity when sintering
is performed, and such target values are determined in advance on the basis of, for
example, values recorded in past operations for manufacturing sintered ore. In the
case where the MgO-containing raw material 17 is added, the amount of the MgO-containing
raw material 17 added may be adjusted in the adjusting process in accordance with
the component concentrations in the sintering raw material measured in the measuring
process.
[0024] In the present embodiment, since the frequency of measurement of the component concentrations
utilizing the infrared analyzer 32 is 128 times per minute, the average component
concentrations for the 128 times is calculated every one minute, and the amounts of
the blast furnace feed materials added are adjusted in accordance with the calculated
average component concentrations every one minute.
[0025] Even in the case where there is a variation in the concentrations of gangue components
in iron ore, by performing this adjusting process, that is, for example, by adjusting
the amount of the CaO-containing raw material 16 added through feedback control in
accordance with the component concentrations in the sintering raw material measured
in the measuring process so that the predetermined target value of the basicity (CaO/SiO
2) of the sintering raw material is achieved, there is a decreased variation in the
basicity (CaO/SiO
2) of the sintering raw material.
[0026] Even in the case where there is a variation in the carbon concentration in dust generated
in a steel plant, by adjusting the amount of the bonding agent 18 added through feedback
control in accordance with the carbon concentration in the sintering raw material
measured in the measuring process so that the predetermined target value of the carbon
concentration in the sintering raw material is achieved, there is a decreased variation
in the carbon concentration in the sintering raw material.
[0027] Even in the case where there is a variation in the water concentration in iron ore
and dust generated in a steel plant, it is possible to perform feedforward control
in which the amount of water 34 added in the drum mixer 36 is determined in accordance
with the water concentration in the sintering raw material measured in the measuring
process and a predetermined target water concentration. Then, by adjusting the amount
of water 34 added in the drum mixer 36 through such feedforward control, it is possible
to achieve the target water concentration in the sintering raw material.
[0028] The sintering machine 40 is, for example, a downward suction-type Dwight-Lloyd sintering
machine. The sintering machine 40 has a sintering raw material feeding device 42,
an endless mobile pallet carriage 44, an ignition furnace 46, gas fuel feeding devices
47, and wind boxes 48. The sintering raw material is charged into the pallet carriage
44 through the sintering raw material feeding device 42 to form a burden layer of
the sintering raw material. The burden layer is ignited by using the ignition furnace
46. By suctioning air downwardly through the wind boxes 48, a gas fuel and oxygen
fed through the gas fuel feeding device 47 disposed above the burden layer is taken
into the burden layer to burn the gas fuel and the bonding agent 18 in the burden
layer while a combustion-melting zone in the burden layer moves toward the lower portion
of the burden layer. With this, the burden layer is sintered to form a sintered cake.
In the present embodiment, the gas fuel is a combustible gas selected from among blast
furnace gas, coke oven gas, a mixture of blast furnace gas and coke oven gas, converter
gas, city gas, natural gas, methane gas, ethane gas, propane gas, and shale gas, and
a mixture thereof.
[0029] Adjustment may be performed in accordance with the component concentrations of the
sintering raw material measured in the measuring process on at least one of a moving
speed of a pallet carriage 44 in the sintering machine 40, the amount of the gas fuel
fed in the sintering machine, and the amount of the oxygen fed in the sintering machine.
[0030] The sintered cake is crushed by using a crushing machine 50 to form sintered ore.
The sintered ore, which has been crushed by using the crushing machine 50, is cooled
by using a cooling machine 60. The sintered ore, which has been cooled by using the
cooling machine 60, is subjected to screening utilizing a sieving apparatus 70 having
plural sieves to separate the sintered ore into product sintered ore 72 having a particle
diameter of more than 5 mm and return ore 74 having a particle diameter of 5 mm or
less. The product sintered ore 72 is transported to a blast furnace 80 via a transporting
conveyer 76 and charged into the blast furnace as a blast furnace feed material. On
the other hand, the return ore 74 is transported to the blending tank 28 in the raw
material feeding apparatus 20 via a transporting conveyer 78. Since the product sintered
ore 72 is sintered ore which has been subjected to crushing by using the crushing
machine 50 followed by cooling and screening, the product sintered ore 72 and the
sintered ore which has been crushed by using the crushing machine 50 have the same
component concentrations. In the present embodiment, the term "particle diameter"
of the product sintered ore 72 or the return ore 74 refers to a particle diameter
determined by performing screening utilizing a sieve, and, for example, the expression
"a particle diameter of more than 5 mm" refers to the particle diameter of particles
which remain on a sieve having a sieve mesh of 5 mm, and the expression "a particle
diameter of 5 mm or less" refers to the particle diameter of particles which pass
through a sieve having a sieve mesh of 5 mm. The value expressing the particle diameter
of the product sintered ore 72 or the return ore 74 is definitely used as an example,
and the particle diameter of the product sintered ore 72 or the return ore 74 is not
limited to this example.
[0031] As described above, in the method for manufacturing sintered ore according to the
present embodiment, the adjusting process is performed in such a manner that at least
one of the amount of the CaO-containing raw material 16 added, the amount of the bonding
agent 18 added, and the amount of water 34 added in the drum mixer 36 is adjusted
in accordance with the component concentrations measured by using the infrared analyzer
32 in the measuring process so that a predetermined target value is achieved. With
this, since there is a decreased variation in the component concentrations in the
sintering raw material, there is a decreased variation in the component concentrations
in the product sintered ore 72 manufactured by using such a sintering raw material,
which results in the quality of the product sintered ore 72 being inhibited from deteriorating.
[0032] For example, in the adjusting process, the amount of the CaO-containing raw material
16 added may be adjusted in accordance with the concentrations of CaO and SiO
2 measured in the measuring process so that the predetermined target value of the basicity
(CaO/SiO
2) of the sintering raw material is achieved. With this, even in the case where iron
ore in which there is a significant variation in the concentrations of gangue components
is used, since there is a decreased variation in the basicity (CaO/SiO
2) of the sintering raw material, there is a decreased variation in the basicity of
the product sintered ore 72 manufactured by using such a sintering raw material, which
makes it possible to manufacture product sintered ore 72 having stable strength. By
using the product sintered ore 72 in which there is a decreased variation in basicity
as a blast furnace feed material, it is possible to make a contribution to the stable
operation of the blast furnace.
[0033] In the case where there is a significant variation in the carbon concentration in
the sintering raw material, there is a significant variation in the heat quantity
when sintering is performed, which results in a significant variation in the FeO concentration
in the product sintered ore 72. In the case where there is a significant variation
in the FeO concentration as described above, at least one of the amount of the bonding
agent 18 added, the amount of the gas fuel fed in the sintering machine, and the amount
of oxygen fed in the sintering machine may be adjusted in the adjusting process so
that the predetermined target value of the heat quantity is achieved when sintering
is performed. With this, since there is a decreased variation in heat quantity when
sintering is performed, there is a decreased variation in the FeO concentration in
the product sintered ore 72.
[0034] In the method for manufacturing sintered ore according to the present embodiment,
the amount of water 34 added in the drum mixer 36 may be adjusted. By adjusting the
amount of water 34 added so that the predetermined target value of the water concentration
is achieved, since there is a decreased variation in the water concentration in the
sintering raw material, there is a further decreased variation in heat quantity when
sintering is performed. With this, there is a further decreased variation in the FeO
concentration in the product sintered ore 72.
[0035] In the case where there is an increase in the FeO concentration due to a variation
in the FeO concentration in the product sintered ore 72, there is a deterioration
in the reducibility of the blast furnace feed materials. In the case where there is
a deterioration in the reducibility of the blast furnace feed materials, since there
is a decrease in the likelihood of an indirect reduction reaction, which is an exothermic
reaction, and since there is an increase in the likelihood of direct reduction reaction,
which is an endothermic reaction, there is a deficiency of heat quantity in the blast
furnace. To compensate for such a deficiency of heat quantity, there is an increase
in the amount of a reducing agent charged into the blast furnace, which results in
an increase in coke ratio in the operation of the blast furnace. Therefore, by controlling
the FeO concentration in the product sintered ore 72 to be equal to a predetermined
target value, it is possible to inhibit the coke ratio in the operation of a blast
furnace from increasing.
[0036] In the case where there is an increase in the temperature of a sintered cake due
to an increase in the heat quantity when sintering is performed, an excessive load
is placed on the cooling machine 60. Therefore, in the case where an increase in the
carbon concentration in the sintering raw material is recognized in the measuring
process, the moving speed of the pallet carriage 44 in the sintering machine may be
decreased when such a sintering raw material is sintered in the sintering machine
40. With this, it is possible to decrease a load placed on the cooling machine 60.
In the measuring process according to the present embodiment, since the component
concentrations in the sintering raw material is continuously measured online, it is
possible to recognize a sudden increase in the carbon concentration. By decreasing
the moving speed of the pallet carriage 44 in the sintering machine in accordance
with such an increase in the carbon concentration, it is possible to prevent the equipment
from being damaged due to an increase in the temperature of the sintered cake.
[0037] In the case where the MgO-containing raw material 17 is added in the sintering raw
material, the amount of MgO-containing raw material 17 added may be adjusted in accordance
with the MgO concentration measured by using the infrared analyzer 32 in the measuring
process so that a predetermined target value of the MgO concentration is achieved.
With this, there is a decreased variation in the concentration of MgO in the product
sintered ore 72. MgO in the product sintered ore 72 is effective for improving softening
and melting property by increasing the melting point. Therefore, by decreasing a variation
in the MgO concentration in the product sintered ore 72, since it is possible to realize
the effect of improving softening and melting property, it is possible to make a contribution
to the stable operation of the blast furnace.
[0038] Although an example, in which sintered ore is manufactured by using the sintering
machine 40 having the gas fuel feeding device 47, is described in the present embodiment,
sintered ore manufacturing equipment having a sintering machine not having the gas
fuel feeding device 47 may be used instead of the sintered ore manufacturing equipment
10 having the sintering machine 40 having the gas fuel feeding device 47. In the case
where a sintering machine not having the gas fuel feeding device 47 is used, at least
one of the amount of the CaO-containing raw material 16 added, the amount of the bonding
agent 18 added, the amount of water 34 added, and the moving speed of the pallet carriage
44 in the sintering machine is adjusted in accordance with the component concentrations
measured in the measuring process. That is, in the present embodiment, it is sufficient
that the gas fuel and oxygen be added as needed in the sintering machine 40 and that
the amount of the gas fuel fed and/or the amount of oxygen fed be adjusted as needed
in the adjusting process.
[0039] Although an example, in which the infrared analyzer 32 is installed in the transporting
conveyer 30 placed between the blending tank 28 and the drum mixer 36 to measure the
component concentrations in the sintering raw material, is described in the present
embodiment, the embodiment of the present invention is not limited to this example.
The infrared analyzer 32 may be installed in the transporting conveyer 14 to measure
the concentration of at least one of total-CaO, SiO
2, MgO, Al
2O
3, FeO, C, and water contained in the iron-containing raw material 12, which is transported
to the blending tank 22, and the infrared analyzer 32 may be installed in the transporting
conveyer 30 between the blending tank 22 and the blending tank 24 to measure the concentration
of at least one of total-CaO, SiO
2, MgO, Al
2O
3, FeO, C, and water contained in the iron-containing raw material 12, which has been
transported from the blending tank 22. A factor having a large effect on a variation
in the component concentrations in the sintering raw material is a variation in the
component concentrations in various brands of iron ore and the dust generated in a
steel plant contained in the iron-containing raw material 12 stored in the yard 11.
Therefore, by installing the infrared analyzer 32 in the transporting conveyer 14
to measure the component concentrations in the iron-containing raw material 12, since
it is possible to perform feedforward control in which at least one of the amount
of the CaO-containing raw material 16 added, the amount of the bonding agent 18 added,
and the amount of water 34 added is determined in accordance with such measured values
and target component concentrations in the sintering raw material, it is possible
to decrease a variation in the component concentrations in the sintering raw material.
Also, by installing the infrared analyzer 32 in the transporting conveyer 14 to measure
the component concentrations in the iron-containing raw material 12, and by adjusting
the moving speed of the pallet carriage 44 in the sintering machine, the amounts of
the gas fuel and/or oxygen fed in the sintering machine in accordance with such measured
values, it is possible to decrease negative effects due to a variation in the heat
quantity when sintering is performed.
[0040] The infrared analyzer 32 may be installed in the transporting conveyer 38 to measure
the concentration of at least one of total-CaO, SiO
2, MgO, Al
2O
3, FeO, C, and water contained in the granulated sintering raw material which is transported
to the sintering machine 40. Since the various raw materials contained in the granulated
sintering raw material are homogeneously mixed in the drum mixer 36 so that there
is no segregation, it is possible to measure the component concentrations in the sintering
raw material with high accuracy. In addition, by adjusting at least one of the amount
of the CaO-containing raw material 16 added, the amount of the bonding agent 18 added,
and the amount of water 34 added through feedback control in accordance with the component
concentrations, it is possible to decrease a variation in the component concentrations
in the sintering raw material. Moreover, the moving speed of the pallet carriage 44
in the sintering machine, the amount of the gas fuel and/or oxygen added may be adjusted
in accordance with such measured values, which makes it possible to decrease negative
effects due to a variation in the heat quantity when sintering is performed.
[0041] Although an example, in which raw materials are discharged from each of the blending
tanks 22 through 28 in the raw material feeding apparatus 20, made into the sintering
raw material in the transporting conveyer 30, and granulated in the drum mixer 36,
is described in the present embodiment, the embodiment of the present invention is
not limited to this example. For example, carbonaceous material-coated particles,
which are manufactured by charging a sintering raw material containing the iron-containing
raw material 12, the CaO-containing raw material 16, and the return ore 74 to the
drum mixer 36, by adding water to the sintering raw material to granulate the sintering
raw material, and by charging the bonding agent 18 in the posterior part of the sintering
time to coat the granulated particles with the bonding agent 18, may be used as a
granulated sintering raw material. In this case, the component concentration in at
least one of the iron-containing raw material 12 and the sintering raw material described
above is measured by using the infrared analyzer 32, and at least one of the amount
of the CaO-containing raw material 16 added, the amount of the bonding agent 18 added,
the amount of the water 34 added, the moving speed of the pallet carriage 44 in the
sintering machine, the amount of the gas fuel fed, and the amount of oxygen fed is
adjusted in accordance with such measured values.
[0042] Carbonaceous material-coated particles, which are manufactured by charging a sintering
raw material containing the iron-containing raw material 12, the CaO-containing raw
material 16, the return ore 74, and part of the bonding agent 18 to the drum mixer
36, by adding water to the sintering raw material to granulate the sintering raw material,
and by charging the remaining bonding agent 18 in the posterior part of the sintering
time to coat the granulated sintering raw material with the bonding agent 18, may
be used as a granulated sintering raw material. Examples of the bonding agent which
is added in the posterior part of the sintering time after water is added to the sintering
raw material include coke breeze and anthracite.
[0043] In the case where plural drum mixers 36 are used and the carbonaceous material-coated
particles which are coated with the bonding agent 18 are used, the carbonaceous material-coated
particles, which are coated with the bonding agent 18, may be manufactured by charging
all or part of the bonding agent 18 into the posterior part of the last drum mixer
36 and by charging the sintering raw material into the drum mixers 36 by using the
method described above. Moreover, regarding water which is added to the sintering
raw material in the case where plural drum mixers 36 are used, all of the water may
be added in the first drum mixer 36, or part of the water may be added in the first
drum mixer 36 with the remaining water being added in the other drum mixers 36.
[0044] Although an example, in which raw materials are discharged from each of the blending
tanks 22 through 28 in the raw material feeding apparatus 20, made into the sintering
raw material in the transporting conveyer 30, and granulated in the drum mixer 36,
is described in the present embodiment, the embodiment of the present invention is
not limited to this example. For example, granulated particles, which are manufactured
by charging a sintering raw material containing the iron-containing raw material 12
and the return ore 74 to the drum mixer 36, by adding water to the sintering raw material
to granulate the sintering raw material, and by charging the CaO-containing raw material
16 or the CaO-containing raw material 16 and the bonding agent 18 in the posterior
part of the sintering time to coat the granulated particles with the CaO-containing
raw material 16 or the CaO-containing raw material 16 and the bonding agent 18, may
be used as a granulated sintering raw material. In this case, the component concentration
in at least one of the iron-containing raw material 12 and the sintering raw material
described above is measured by using the infrared analyzer 32, and at least one of
the amount of the CaO-containing raw material 16 added, the amount of the bonding
agent 18 added, the amount of the water 34 added, the moving speed of the pallet carriage
44 in the sintering machine, the amount of the gas fuel fed in the sintering machine,
and the amount of oxygen fed in the sintering machine is adjusted in accordance with
such measured values.
[0045] Granulated particles, which are manufactured by charging a sintering raw material
containing the iron-containing raw material 12, the return ore 74, and part of the
CaO-containing raw material 16 or part of the CaO-containing raw material 16 and part
of the bonding agent 18 to the drum mixer 36, by adding water to the sintering raw
material to granulate the sintering raw material, and by adding the remaining CaO-containing
raw material 16 and the remaining bonding agent 18 in the posterior part of the sintering
time to coat the granulated sintering raw material with the CaO-containing raw material
16 and the bonding agent 18, may be used as a granulated sintering raw material.
[0046] In the case where plural drum mixers 36 are used and the granulated particles which
are coated with the CaO-containing raw material 16 or the CaO-containing raw material
16 and the bonding agent 18 are used, the granulated particles, which are coated with
the CaO-containing raw material 16 and the bonding agent 18, may be manufactured by
charging all or part of the CaO-containing raw material 16 and the bonding agent 18
into the posterior part of the last drum mixer 36 and by charging the sintering raw
material into the drum mixers 36 by using the method described above.
[0047] Although an example, in which raw materials are discharged from each of the blending
tanks 22 through 28 in the raw material feeding apparatus 20 and made into the sintering
raw material in the transporting conveyer 30, is described in the present embodiment,
the embodiment of the present invention is not limited to this example. For example,
parts of the respective raw materials discharged from each of the blending tanks 22
through 28 in the raw material feeding apparatus 20 are directly transported to the
drum mixer 36 via the transporting conveyer 30, and the remaining parts of the respective
raw materials are transported to a high-speed stirring apparatus via a transporting
conveyer, which is different from the transporting conveyer 30, so as to be subjected
to a stirring treatment. Subsequently, such remaining parts may be charged into the
transporting conveyer 30 or the transporting conveyer 38 after having been subjected
to granulation utilizing a granulating machine, such as a drum mixer or a pelletizer,
optionally followed by drying utilizing a drying machine as needed. Also, such remaining
parts may be directly charged into the transporting conveyer 30 after having been
subjected to a stirring treatment without being subjected to granulation utilizing
the granulating machine, such as a drum mixer or a pelletizer. Moreover, a crushing
process and/or a sieving process may be performed before a stirring treatment is performed
by using the high-speed stirring apparatus. In the case where plural drum mixers 36
are used, such remaining parts may be charged into any one of transporting conveyers
placed between the drum mixers.
[0048] Although an example, in which the infrared analyzer 32 in the measuring process is
installed in the transporting conveyer 30 placed between the blending tank 28 and
the drum mixer 36, is described in the present embodiment, the embodiment of the present
invention is not limited to this example. For example, the infrared analyzer 32 may
be installed in the transporting conveyer 14 placed between the yard 11 and the blending
tank 22, which is closest to the entrance among the blending tanks, in the transporting
conveyer 30 placed between the blending tank 22 and the blending tank 24, or in the
transporting conveyer 38 placed between the drum mixer 36 and the sintering machine
40. However, in the case where the granulated particles coated with the bonding agent
18 or the CaO-containing raw material 16 and the bonding agent 18 are used, since
the components in the surface layer may have an effect on the measurement of the component
concentrations, it is preferable that the infrared analyzer 32 be installed in the
transporting conveyer 14, in the transporting conveyer 30 placed between the blending
tank 22 and the blending tank 24, or in the transporting conveyer 30 placed between
the blending tank 28 and the drum mixer 36.
[0049] In the measuring process, not only one but plural infrared analyzers 32 may be installed.
Two or more infrared analyzers 32 may be installed in the transporting conveyer 14,
in the transporting conveyer 30 placed between the blending tank 22 and the blending
tank 24, in the transporting conveyer 30 place between the blending tank 28 and the
drum mixer 36, and in the transporting conveyer 38. The component concentrations in
two or all of the sintering raw material, the iron-containing raw material 12, and
granulated sintering raw material may be measured by using plural infrared analyzers,
and at least one of the amount of CaO-containing raw material 16 added, the amount
of the bonding agent 18 added, the amount of the water 34 added, the moving speed
of the pallet carriage 44 in the sintering machine, the amount of the gas fuel fed
in the sintering machine, and the amount of oxygen fed in the sintering machine may
be adjusted in accordance with such measured values.
EXAMPLES
(Example 1)
[0050] In the case of both of example 1 of the present invention and comparative example
1, product sintered ore was manufactured by using the sintered ore manufacturing equipment
10 illustrated in Fig. 1. In the case of example 1 of the present invention, the product
sintered ore was manufactured for 36 hours while the component concentrations in the
sintering raw material were continuously measured by using the infrared analyzer 32
installed in the transporting conveyer 30 and the amount of the CaO-containing raw
material 16 added was adjusted in accordance with the measured component concentrations
so that the target value of the basicity (CaO/SiO
2) of the sintering raw material was achieved. On the other hand, in the case of comparative
example 1, the product sintered ore was manufactured for 36 hours while the component
concentrations in the sintering raw material were not continuously measured but measured
offline every 2 hours, and the amount of the CaO-containing raw material 16 added
was adjusted in accordance with the measured component concentrations so that the
target value of the basicity (CaO/SiO
2) of the sintering raw material was achieved.
[0051] Fig. 2 includes graphs illustrating the variations of the basicity of a sintering
raw material and the drop strength of product sintered ore in the case of example
1 of the present invention. Fig. 3 includes graphs illustrating the variations of
the basicity of a sintering raw material and the drop strength of product sintered
ore in the case of comparative example 1. The term "basicity" in Fig. 2(a) and Fig.
3(a) refers to the total-CaO concentration divided by the SiO
2 concentration in the sintering raw material. The term "drop strength" in Fig. 2(b)
and Fig. 3(b) refers to the strength measured by using the testing method for drop
strength prescribed in JIS M 8711.
[0052] As indicated in Fig. 2(a) and Fig. 2(b), in the case of example 1 of the present
invention, there was a decreased deviation from the target basicity of the sintering
raw material, and there was a decreased variation in the drop strength of the product
sintered ore. In the case of example 1 of the present invention, the component concentrations
in the sintering raw material were continuously measured. Therefore, even in the case
where there was a sudden variation in the component concentrations, it was possible
to promptly detect such a variation in the component concentrations and to promptly
adjust the amount of the CaO-containing raw material 16 added so that the target values
of the component concentrations were achieved. With this, in the case of example 1
of the present invention, it was possible to decrease the deviation from the target
basicity of the sintering raw material and a variation in the basicity and also to
decrease a variation in the drop strength of the product sintered ore.
[0053] On the other hand, as indicated in Fig. 3(a) and Fig. 3(b), in the case of comparative
example 1, there was a significant deviation from the target basicity of the sintering
raw material, there was a significant variation in the drop strength of the product
sintered ore, and product sintered ore having low drop strength was manufactured.
In the case where there is a decrease in the drop strength of the product sintered
ore, since the product sintered ore is easily crushed due to impact when the product
sintered ore is transported to or charged into a blast furnace, there is a variation
in the particle size of the product sintered ore. It is not preferable that there
be a variation in the particle size of the product sintered ore, because this causes
a disturbed burden distribution in a blast furnace.
[0054] From these results, it is clarified that, by using the manufacturing method according
to example 1 of the present invention, it is possible to manufacture product sintered
ore in which there is a decreased variation in the component concentrations and in
the drop strength.
(Example 2)
[0055] In the case of both of example 2 of the present invention and comparative example
2, product sintered ore was manufactured by using the sintered ore manufacturing equipment
10 illustrated in Fig. 1. In the case of example 2 of the present invention, the product
sintered ore was manufactured for 36 hours while the carbon concentration in the sintering
raw material was continuously measured by using the infrared analyzer 32 installed
in the transporting conveyer 30 and the amount of the bonding agent 18 added was adjusted
in accordance with the measured carbon concentration so that the target value of the
carbon concentration in the sintering raw material was achieved. On the other hand,
in the case of comparative example 2, the product sintered ore was manufactured for
36 hours while the carbon concentration in the sintering raw material was not continuously
measured but measured offline every 4 hours, and the amount of the bonding agent 18
added was adjusted in accordance with the measured carbon concentration so that the
target value of the carbon concentration in the sintering raw material was achieved.
The target value of the carbon concentration in the sintering raw material was determined
on the basis of the necessary amount of carbon derived by calculating a sintering
temperature in accordance with the component concentrations in the sintering raw material
so that the liquid phase rate of the sintering raw material when sintering was performed
was within a preferable range and by calculating the amount of carbon necessary for
generating combustion heat to achieve the calculated sintering temperature. In the
case of both of example 2 of the present invention and comparative example 2, the
sintering raw material was changed to one having a higher carbon concentration during
a specific period of time in the middle of the manufacturing time for the product
sintered ore, and, thereafter, the sintering raw material was changed back to the
original one to continue to produce the product sintered ore.
[0056] Fig. 4 includes graphs illustrating the variations of the production rate of the
sintering machine, the carbon concentration in a sintering raw material, and the moving
speed of a pallet carriage in the case of example 2 of the present invention. Fig.
5 includes graphs illustrating the variations of the production rate of the sintering
machine, the carbon concentration in a sintering raw material, and the moving speed
of a pallet carriage in the case of comparative example 2. Fig. 4(a) and Fig. 5(a)
illustrate the variation of the production rate (t/(h × m
2)) of the sintering machine. The expression "the production rate (t/(h × m
2)) of a sintering machine" refers to the mass (t) of a sintered cake produced by a
sintering machine per one hour divided by the area (m
2) of a pallet carriage. Fig. 4(b) and Fig. 5(b) illustrate the variation of the carbon
concentration (mass%) in the sintering raw material. Fig. 4(c) and Fig. 5(c) illustrate
the variation of the moving speed (m/min) of the pallet carriage. In both of Fig.
4 and Fig. 5, the portions defined by the dashed lines indicate a "period of raw material
change", during which the sintering raw material having a higher carbon concentration
was used.
[0057] In the case of example 2 of the present invention, the carbon concentration in the
sintering raw material was continuously measured, and the amount of the bonding agent
18 added was adjusted so that the target value of the carbon concentration was achieved.
By continuously measuring the component concentrations in the sintering raw material
like this, since it was possible to detect an increase in the carbon concentration
in the early stage of the period of raw material change, the amount of the bonding
agent 18 added was promptly adjusted in accordance with the measured concentration
so that the target value of the carbon concentration in the sintering raw material
was achieved. With this, since an increase in the carbon concentration in the sintering
raw material was inhibited as illustrated in Fig. 4(b), it was possible to manufacture
sintered ore without decreasing the moving speed of the pallet carriage as illustrated
in Fig. 4(c), which resulted in no significant decrease in the production rate of
the sintering machine 40 as illustrated in Fig. 4(a).
[0058] On the other hand, in the case of comparative example 2, since the carbon concentration
in the sintering raw material was not continuously measured, the detection of an increase
in the carbon concentration in the sintering raw material was delayed. Therefore,
as illustrated in Fig. 5(b), there was a significant increase in the carbon concentration
in the sintering raw material. In the case where there is an excessive increase in
the temperature of a sintered cake due to an increase in the carbon concentration,
since an excessive load is placed on the cooling machine 60, it is necessary to decrease
the moving speed of the pallet carriage to decrease a load placed on the cooling machine
60. Therefore, the moving speed of the pallet carriage was decreased as illustrated
in Fig. 5(c), which resulted in a significant decrease in the production rate of the
sintering machine 40 as illustrated in Fig. 5(a).
[0059] As described above, by using the manufacturing method according to example 2 of the
present invention, even in the case where there is a variation in the carbon concentration
in the sintering raw material, since it is possible to promptly detect such a variation
in the carbon concentration, it is possible to promptly adjust the amount of the bonding
agent 18 added in response to such a variation in the carbon concentration. It is
clarified that, with this, since there is a decreased variation in heat quantity when
sintered ore is manufactured due to a decreased variation in the carbon concentration
in the sintering raw material, an increase in the temperature of product sintered
ore is inhibited, which results in a decrease in the production rate of the sintering
machine 40 being inhibited.
Reference Signs List
[0060]
- 10
- sintered ore manufacturing equipment
- 11
- yard
- 12
- iron-containing raw material
- 14
- transporting conveyer
- 16
- CaO-containing raw material
- 17
- MgO-containing raw material
- 18
- bonding agent
- 20
- raw material feeding apparatus
- 22
- blending tank
- 24
- blending tank
- 25
- blending tank
- 26
- blending tank
- 28
- blending tank
- 30
- transporting conveyer
- 32
- infrared analyzer
- 34
- water
- 36
- drum mixer
- 38
- transporting conveyer
- 40
- sintering machine
- 42
- sintering raw material feeding device
- 44
- pallet carriage
- 46
- ignition furnace
- 47
- gas fuel feeding device
- 48
- wind box
- 50
- crushing machine
- 60
- cooling machine
- 70
- sieving apparatus
- 72
- product sintered ore
- 74
- return ore
- 76
- transporting conveyer
- 78
- transporting conveyer
- 80
- blast furnace