AU2018256247B2 - Method for smelting ilmenite using red mud - Google Patents
Method for smelting ilmenite using red mud Download PDFInfo
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- AU2018256247B2 AU2018256247B2 AU2018256247A AU2018256247A AU2018256247B2 AU 2018256247 B2 AU2018256247 B2 AU 2018256247B2 AU 2018256247 A AU2018256247 A AU 2018256247A AU 2018256247 A AU2018256247 A AU 2018256247A AU 2018256247 B2 AU2018256247 B2 AU 2018256247B2
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- titanium dioxide
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/02—Magnetic separation acting directly on the substance being separated
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
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- Inorganic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The present invention provides a method for smelting ilmenite using red mud, the method comprising the steps of: mixing an ilmenite concentrate and red mud to form a mixture; adding a carbon source to the mixture, followed by heating to reduce iron in the mixture to form a molten droplet; subjecting the molten droplet to magnetic separation to remove the iron and recover a titanium dioxide slag; introducing the titanium dioxide slag into a Bayer process to recover alumina (Al
Description
[Invention Title]
[Technical Field]
The present disclosure is related to a method of
smelting ilmenite which is an ore for titanium,
particularly to a method of smelting ilmenite whereby a
high quality of titanium dioxide can be obtained and
process byproducts can be recovered and utilized.
[Background Art]
The titanium raw material industry producing titanium is
dominated by ilmenite produced from heavy sand ore deposits
in Australia, South Africa, India regions or from hard rock
ore deposits in Canada and Norway. Australia is the world's
largest producer of heavy ore concentrates and more than
half of ilmenite is produced as synthetic rutile and used
as pigment raw material.
Ilmenite can be used directly in the production of
titanium dioxide pigments, but most of ilmenite is improved
in its quality by producing a titanium dioxide slag or
synthetic rutile.
Another important raw material is natural rutile, which
is produced as a by-product of ilmenite in Australia, the
United States and South Africa and as the main mineral in
Sierra Leone.
Ilmenite (FeO•TiO2) has a content of generally 45 to 65%
by weight of TiO 2 . Due to advances in chemical and dry smelting technology, it is possible to remove iron component to improve the TiO 2 content in synthetic rutile up to 90 ~ 96%.
As a commercial process for preparing artificial rutile
from ilmenite, there is the Becher process.
In the Becher process, artificial rutile is prepared
through a two-step process of reduction and aeration.
In the first step, ilmenite is coated with iron using
sub-bituminous coal as fuel and reducing agent at a high
temperature of 1300 0C. The reaction proceeds according to
Reaction Scheme 1 below.
[Reaction Scheme 1]
Fe203•TiO2 + 3CO - (2Fe + TiO 2 ) + 3CO2
The iron component is oxidized by blowing air in an
ammonium chloride solution at a temperature up to 80 0C
(aeration).
Using a hydrocyclone, artificial rutile (TiO 2 , 90%) with
a standard quality is separated from hydrous iron oxide
concentrated and pumped to a reservoir, and the general
reaction is performed according to Reaction Scheme 2 below.
[Reaction Scheme 2]
(2Fe + TiO 2 ) + 02 - 2FeO + TiO 2
At this time, when reducing at 1300 °C in the course of
using iron, it is impossible to physically separate the reduced iron. Therefore, iron is again oxidized to an oxide in the subsequent aeration process and then subjected to acid leaching, thereby separating and recovering iron and improving the quality of titanium dioxide.
According to the conventional Becher process, since the
reduced iron produced in the reduction process cannot be
separated in advance and the purity of titanium dioxide is
increased afterwards through the aeration and acid leaching
processes, the load of the aeration and acid leaching
processes is greatly increased.
Meanwhile, red mud is a workplace waste generated from a
bauxite refining process and consists of a strong alkaline
material with a water content of 40-55% and a pH of 11~13.
In addition, although hydrous aluminum silicate and quartz
are contained in a large amount, a utilization method thereof
has not been disclosed yet. Since red mud is strongly
oxidative and thus difficult to treat, the development of new
utilization methods is desperately needed.
As prior literatures related thereto, Korea Laid-Open
Patent Publication No. 10-2017-0021759 (Publication date:
2017.02.28) discloses a fabrication method of metal titanium
using an ilmenite ore.
Any discussion of documents, acts, materials, devices,
articles or the like which has been included in the present
specification is not to be taken as an admission that any or
all of these matters form part of the prior art base or were
common general knowledge in the field relevant to the present
disclosure as it existed before the priority date of each of
the appended claims.
Throughout this specification the word "comprise", or
variations such as "comprises" or "comprising", will be
understood to imply the inclusion of a stated element, integer
or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
Summary
In one aspect of the invention there is provided a method
for smelting ilmenite using red mud, comprising the steps of:
(a) mixing an ilmenite concentrate and red mud to form a
mixture;
(b) adding a carbon source to the mixture, followed by
heating to reduce iron in the mixture;
(c) separating reduced iron through a magnetic separation;
and
(d) subjecting residue to aeration and acid-leaching to
remove iron in the residue and recover titanium dioxide,
wherein said red mud is added from 10 to 200 parts by
weight based on a total of 100 parts by weight of the ilmenite
concentrate,
wherein, in the step of mixing an ilmenite concentrate and
red mud to form a mixture, the mixture is pressurized to form
a briquette, and
wherein, in the step of adding a carbon source to the mixture,
iron oxide contained in the red mud changes to reduced iron.
In another aspect of the invention there is provided a
method for smelting ilmenite using red mud, comprising the
steps of:
(i) mixing an ilmenite concentrate and red mud to form a
mixture;
(ii) adding a carbon source to the mixture, followed by
heating to reduce iron in the mixture to form molten droplets;
(iii) physically separating the molten droplets to remove
the iron and recover a titanium dioxide slag;
(iv) introducing the titanium dioxide slag into a Bayer
process to recover alumina (A1 2 0 3 ); and
(v) subjecting the alumina-separated titanium dioxide slag
to acid-leaching to remove silica (SiO2 ); wherein said Bayer process is performed by adding 1.25 to
6.25M of caustic soda (NaOH) to titanium dioxide slag to leach
alumina,
wherein, in the step of mixing an ilmenite concentrate and
red mud to form a mixture, the mixture is pressurized to form
a briquette, and
wherein, in the step of adding a carbon source to the
mixture, iron oxide contained in the red mud changes to
reduced iron.
[Detailed Description of the Invention]
[Technical Problem] Therefore, the present disclosure is related to a method of
smelting ilmenite using red mud, and provides a method of
smelting ilmenite using red mud which is waste difficult to
utilize, since red mud which was conventionally difficult to
utilize can be used as flux or raw material to smelt ilmenite
and recover highly pure titanium dioxide.
It is possible to improve the efficiency of the process by
increasing the quality of titanium dioxide recovered from the
smelting process and simultaneously to provide a new
utilization method of red mud by separating alumina (A1 2 0 3 ) which has been included in the red mud added as flux.
The problem to be solved by the present disclosure is not
limited to the problem(s) mentioned above, and other aspect(s)
not mentioned will be clearly understood by those skilled in
the art from the following description.
[Technical Solution] In order to solve the above problems, the present
disclosure is directed to provide a method for smelting
ilmenite using red mud, including a step of mixing an ilmenite
concentrate and red mud to form a mixture, a step of adding a
carbon source to the mixture, followed by heating to reduce
iron in the mixture, a step of separating the reduced iron
4A through magnetic separation; and a step of subjecting residue to aeration and acid-leaching to remove iron in the residue and recover titanium dioxide.
In order to solve the above problems, the present
disclosure is also directed to provide a method for smelting
ilmenite using red mud, including (a) a step of mixing an
ilmenite concentrate and red mud to form a
4B mixture; (b) a step of adding a carbon source to the mixture, followed by heating to reduce iron in the mixture to form molten droplets; (c) a step of physically separating the molten droplets to remove the iron and recover a titanium dioxide slag; (d) a step of introducing the titanium dioxide slag into a Bayer process to recover alumina (A1 2 0 3 ); and (e) a step of subjecting the alumina separated titanium dioxide slag to acid-leaching to remove silica (SiO 2 ) .
[Advantageous Effects]
According to the present disclosure, red mud which is
generated from the process of smelting aluminum oxide and
difficult to treat can be treated together in the process
of smelting ilmenite by using as flux or raw material.
Also, when red mud and ilmenite concentrate are mixed
and heated to be reduced, iron and titanium dioxide
contained in ilmenite as well as iron and titanium dioxide
contained in red mud can be separated and recovered all at
once and thus the recovery efficiency of iron and titanium
dioxide can be largely improved.
In addition, it is possible to largely improve the
quality of titanium dioxide slag that remains after
physically sorting and separating iron which is an impurity
contained in ilmenite, not by reducing the iron at a high
temperature, but by reducing with red mud to form molten
droplets.
Also, it is possible to dramatically reduce the cost for
the process of smelting ilmenite since an aeration step for
recovering a high-quality titanium dioxide is not necessary,
by minimizing iron content, an impurity in the titanium
dioxide slag that is recovered by separating and recovering
iron reduced through a reduction process wherein a carbon
source is added to adjust a heating temperature and
magnetic separation
Also, in the process of smelting titanium dioxide using
ilmenite concentrate, it is possible to recover a high
quality titanium dioxide and obtain an iron scrap as a by
product by utilizing red mud which is a waste material that
is very difficult to treat, and the alumina contained in
red mud is recovered, thus it is very environmentally
friendly.
[Description of the Drawings]
FIG. 1 is a process flow chart of the method of smelting
ilmenite using red mud according to an embodiment of the
present disclosure.
FIG. 2 is a process flow chart of the method of smelting
ilmenite using red mud according to another embodiment of
the present disclosure.
FIG. 3 is a photograph of ilmenite, red mud and free
burning coal samples which are starting materials in the
method of smelting ilmenite using red mud according to an
embodiment of the present disclosure.
FIG. 4 is a photograph showing molten droplets of iron
reduced by heating in the method of smelting ilmenite using
red mud according to an embodiment of the present
disclosure.
FIG. 5 is a schematic diagram showing the configuration
of the method of smelting ilmenite using red mud according
to another embodiment of the present disclosure.
FIG. 6 is a photograph of a high temperature and high
pressure leaching apparatus.
FIG. 7 is a graph showing alumina and silica contents
depending on caustic soda concentration in the Bayer
process step in the method of smelting ilmenite using red
mud according to another embodiment of the present
disclosure.
[Best Mode for carrying out the Disclosure]
FIG. 5 is a schematic diagram showing the configuration
of the method of smelting ilmenite using red mud according
to another embodiment of the present disclosure.
Referring to FIG. 5, a mixture of ilmenite concentrate
100 g and red mud 100 g was pressurized to prepare
briquettes.
Powdered ilmenite concentrate and red mud were uniformly
mixed through a ball mill and then briquetted using a
pelletizer with a pressure of 5 tons at maximum.
A free-burning coal was added to the briquette, which
was reduced by heating at 1700 °C for 15 minutes in a rotary furnace.
It was confirmed that a high-temperature melt occurred
and the resulting molten droplets and residue were
identified.
The molten droplets were separated using a magnetic
separator.
The titanium dioxide slag was recovered by removing
molten droplets.
FIG. 6 is a photograph of a high temperature and high
pressure leaching apparatus.
Referring FIG. 6, in the high temperature and high
pressure leaching apparatus was charged caustic soda
together with titanium dioxide slag from which molten
droplets were removed and a leaching was made under a
condition of 200 °C and 20 bar for 1 hour.
After leaching, leached components were analyzed to
determine the content of alumina and silica in the titanium
dioxide slag.
An acid-leaching was performed by adding sulfuric acid
at a concentration of 30% to titanium dioxide slag from
which alumina was removed.
The quality of the finally-recovered titanium dioxide
slag was determined.
[Mode for carrying out the Invention]
Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
The advantages and features of the present disclosure
and the manner of achieving them will be apparent by
reference to various embodiments described in detail below
with reference to the accompanying drawings.
However, the present disclosure is not limited to the
embodiments described below, but may be embodied in various
other forms, and these embodiments are provided in order to
complete the disclosure of the present disclosure and to
completely inform those of ordinary skill in the art of the
scope of the present disclosure. The present disclosure is
only defined by the appended claims.
Also, in the following description of the present
disclosure, a detailed description of a configuration that
is considered to unnecessarily obscure the gist of the
present disclosure, for example, a known technology
including the prior art, may be omitted.
FIG. 1 is a process flow chart of the method of smelting
ilmenite using red mud according to an embodiment of the
present disclosure.
Referring FIG. 1, the method for smelting ilmenite using
red mud according to another embodiment of the present
disclosure includes mixing an ilmenite concentrate and red
mud to form a mixture in step S100, adding a carbon source
to the mixture, followed by heating to reduce iron in the mixture in step S200, separating the reduced iron through a magnetic separation in step S300 and subjecting the residue to aeration and acid-leaching to remove iron in the residue and recover titanium dioxide in step S400.
The ilmenite concentrate may be those that the quality
is improved by beneficiation of ilmenite ore.
The ilmenite concentrate may contain titanium dioxide
(TiO 2 ) in 17 to 50 % by weight.
The quality of ilmenite concentrate is generally 45 % to
50 %, but the higher the quality of titanium is, the higher
the process cost is.
In addition, since domestic ilmenites generally have a
low quality of 17% to 50%, it is very difficult to use them
for smelting titanium dioxide, but when a low-quality
ilmenite concentrate and red mud are mixed and smelted, a
high-quality titanium dioxide can be obtained.
The ilmenite concentrate may contain titanium dioxide
and remained iron oxide (FeOx) in 35 to 65 % by weight.
The iron oxide is reduced and recovered by separating at
the step of a magnetic separation
The red mud may be a waste generated from a smelting
process of aluminum oxide.
The red mud has a high pH and thus difficult to dispose
of as itself, but when mixed with ilmenite concentrate and
then reduced, iron and titanium dioxide contained in red
mud may be separately recovered.
The red mud can contain titanium dioxide (TiO 2 ) at 5 to
10 % by weight.
Titanium dioxide contained in the red mud may be
recovered together with titanium dioxide contained in
ilmenite concentrate.
The red mud may contain remaining hematite (Fe203) at 30
to 40 % by weight in addition to titanium dioxide.
Iron oxide contained in red mud may be hematite.
The hematite in red mud may be reduced together with
iron oxide component of ilmenite concentrate and can be
physically separated.
The red mud may be added in an amount of 10 to 200 parts
by weight based on 100 parts by weight of the total amount
of ilmenite concentrate.
Iron oxide contained in the red mud has a very fast
reduction rate compared to ilmenite and thus firstly
changes to reduced iron.
The resulting reduced iron is carburized by carbon and
has a low melting point and acts as a strong reducing agent
by itself to facilitate the reduction of ilmenite and to
greatly increase the production of molten droplets of
reduced iron.
When the red mud is added in less than 10 parts by
weight, the purity of titanium dioxide separated and
recovered becomes low, and when it exceeds 200 parts by
weight, there may be a problem that the efficiency of the
process of reducing iron by heating becomes greatly low.
In the step of forming a mixture by mixing ilmenite concentrate and red mud, the mixture may be pressed to form a briquette (pellet).
In the case of forming the mixture into briquettes, the
efficiency of the subsequent heating and reducing step may
be greatly improved, and the convenience of process
operation may be greatly increased in a reduction process
using a rotary furnace or a sintering furnace.
The carbon source may be any one selected from free
burning coals consisting of peat, brown coal and bituminous
coal.
The carbon source may increase the reaction temperature
in the step of heating and reducing the mixture, and the
reduced iron reduced by carbon may become a very strong
reducing agent to greatly improve the efficiency of the
reduction step.
The carbon source may be added in 10 to 100 parts by
weight based on total 100 parts by weight of the mixture.
When the carbon source is added in less than 10 parts by
weight, it is difficult to increase the temperature to a
temperature required for the reduction reaction, and when
the carbon source exceeds 100 parts by weight, an extra
amount of carbon source may be added to increase the
process cost, thereby reducing the overall efficiency.
Here, when the carbon source is set to maximum within
the above range, a maximum reduction rate may be expected,
and there is an advantage in that any unreacted residual
carbon can be recovered and reused.
The iron in the mixture can be reduced by adding a
carbon source to the mixture and heating to 1350 to 1500 0C
for 8 to 12 hours.
When heated below 1350 0C, the mixture of ilmenite
concentrate and red mud does not reach the melting
temperature and thus does not melt. When heated within the
above range, it is possible to proceed the reduction
roasting sufficiently, to control the composition of
components such as alumina, silica, and the like in the
produced slag, and to physically separate the reduced iron
component.
The above heating can be performed at a sintering
furnace or a rotary furnace.
When using a sintering furnace (sinter bed) or a rotary
furnace (rotary kiln), it is possible to easily heat to a
setting temperature by adding a carbon source, and it is
very advantageous to adjust the reaction temperature and
reaction time during progressing the reducing reaction by
heating.
The above reduced iron can be formed in a molten droplet
shape.
When ilmenite concentrate and red mud are mixed and
heated, iron of the iron oxide component in ilmenite
concentrate and the iron oxide contained in red mud is
reduced and discharged, and at this time, discharged in a
molten droplet shape. The reduced iron can be separated
through a magnetic separation in step S300.
When the reduced iron is formed in a molten droplet
shape, iron components are agglomerated and easily
attracted to magnetism, and iron components in ilmenite
concentrate and red mud can be together separated by one
process through a magnetic separation.
When iron is separated in advance through a magnetic
separation, the load to the aeration and acid-leaching
described later will be largely decreased.
In addition, iron is separated and removed from the
residue, the content of titanium dioxide issued from
ilmenite concentrate and red mud is increased, and thus the
quality of titanium dioxide to be recovered is very
improved.
The above residue is titanium dioxide slag.
Thereafter, the residue is subjected to aeration and
acid-leaching to recover titanium dioxide in the residue in
step S400.
The aeration can be made by introducing air into the
residue for 30 minutes to 30 hours.
In case of not reaching to the above range, it is
difficult to remove iron component remaining in the residue.
The acid-leaching can remove iron in the residue by
using from 0.05% to 30% of sulfuric acid and leaching for 5
minutes to 10 hours.
The concentration of sulfuric acid can vary depending on
the nature of the residue and can be selected on the
relation of inverse proportion to the leaching time.
In the acid-leaching step, all iron components in the
residue can be removed.
In the above aeration and acid-leaching step, all the
gangue component can be removed, the iron component in the
residue and the quality of titanium dioxide to be removed
is greatly improved.
The above titanium dioxide has a quality of 88% to 95%.
Therefore, it is possible to provide a new smelting
method which can recover titanium dioxide with a high
purity by using as raw materials ilmenite with a very low
quality and red mud which is difficult to dispose of.
In the smelting method according to an embodiment of the
present disclosure, therefore, iron oxide contained in red
mud is firstly reduced under a carbon source, and the
reduced iron is then carburized by the carbon source to
have a low melting point and thereby acts as a strong
reducing agent, which facilitates the reduction of ilmenite
and promotes the production of reduced iron into molten
droplets.
In addition, a high-quality titanium dioxide is
recovered by effectively removing iron from the residue
through aeration and acid-leaching.
FIG. 2 is a process flow diagram of the method of
smelting ilmenite using red mud according to another
example of the present disclosure.
Referring to FIG. 2, the method of smelting ilmenite
using red mud according to another embodiment of the present disclosure includes mixing an ilmenite concentrate and red mud to form a mixture in step F100, adding a carbon source to the mixture, followed by heating to reduce iron in the mixture to form molten droplets in step F200, subjecting the molten droplets to a magnetic separation to remove the iron and recover a titanium dioxide slag in step
F300, introducing the titanium dioxide slag into a Bayer
process to recover alumina (A12 0 3 ) in step F400, and
subjecting the alumina-separated titanium dioxide slag to
acid-leaching to remove silica (SiO 2 ) in step F500.
First, an ilmenite concentrate and red mud are mixed to
form a mixture in step F100.
The ilmenite concentrate may be any one of which quality
is improved by beneficiation of ilmenite ore.
The ilmenite concentrate may contain titanium dioxide
(TiO 2 ) in 17 to 50 % by weight.
The quality of ilmenite concentrate is generally 45 % to
50 %, but the higher the quality of titanium is, the higher
the process cost is.
In addition, since domestic ilmenite generally has a low
quality of 17% to 50%, it is very difficult to use it for
smelting titanium dioxide, but when a low-quality ilmenite
concentrate and red mud are mixed and smelted, a high
quality titanium dioxide can be obtained.
The ilmenite concentrate may contain titanium dioxide
and remained iron oxide (FeOx) in 35 to 65 %.
The iron oxide is reduced and recovered by separating in a magnetic separation step.
The red mud may be a waste generated from a process of
smelting aluminum oxide.
Red mud includes titanium dioxide (TiO 2 ), alumina (A1 2 0 3
) and silica (SiO 2 ).
Red mud is difficult to dispose as itself due to its
very high pH, but when mixed with ilmenite concentrate and
then reduced, iron and titanium dioxide contained in red
mud can be separated and recovered.
Red mud can contain titanium dioxide (TiO 2 ) in 5 to 10
% by weight.
Titanium dioxide contained in red mud can be recovered
together with titanium dioxide contained in ilmenite
concentrate.
Red mud includes alumina and silica.
The alumina and silica can be contained in titanium
dioxide slag generated from the reduction process. In this
case, since the quality of titanium dioxide is decreased, a
step to remove the alumina and silica is needed, and thus a
high-quality titanium dioxide can be obtained.
Said red mud may contain residual hematite (Fe203) in 30
to 40 wt% in addition to titanium dioxide.
The hematite in the red mud is reduced together with the
iron component of the ilmenite concentrate to form molten
droplets and can be physically separated through a magnetic
separation.
Iron oxide contained in the red mud has a very fast reduction rate compared to ilmenite and thus firstly changes to reduced iron.
The resulting reduced iron is carburized by carbon and
has a low melting point and acts as a strong reducing agent
by itself to facilitate the reduction of ilmenite and to
increase the production of molten droplets which are
reduced iron.
The red mud is added in an amount of 10 to 200 parts by
weight based on 100 parts by weight of the total amount of
ilmenite concentrate.
When the red mud is added in less than 10 parts by
weight, the quality of titanium dioxide separated and
recovered does not reach 97%, when it exceeds 200 parts by
weight, a problem may occur that the efficiency of the
process of reducing iron by heating becomes very low.
In the step of forming a mixture by mixing ilmenite
concentrate and red mud, the mixture may be pressed to form
briquettes (pellets).
In the case of forming the mixture into briquettes, the
efficiency of the subsequent heating and reducing step may
be greatly improved, and the convenience of process
operation may be greatly increased in a reduction process
using a rotary furnace or a sintering furnace.
A carbon source is added to the mixture, which is heated
to reduce iron in the mixture to form molten droplets in
step S200.
The carbon source may be any one selected from free burning coals consisting of peat, brown coal, bituminous coal and the like.
The carbon source has a high volatility.
The carbon source may increase the reaction temperature
in the step of heating and reducing the mixture, and the
reduced iron reduced by carbon may become a very strong
reducing agent to greatly improve the efficiency of the
reduction step.
The carbon source may be added in 10 to 100 parts by
weight based on total 100 parts by weight of the mixture.
When the carbon source is set to maximum, a maximum
reduction rate may be expected, and there is an advantage
in that any unreacted residual carbon can be recovered and
reused.
When the carbon source is added in less than 10 parts by
weight, it is difficult to increase the temperature to a
temperature required for the reduction reaction, and when
the carbon source exceeds 100 parts by weight, an extra
amount of carbon source may be added to increase the
process cost, thereby reducing the overall efficiency.
The iron in the mixture can be reduced and roasted by
adding a carbon source to the mixture and heating to 1400
to 2000 0C for 15 minutes to 10 hours.
When heated below 1400 0C, the mixture of ilmenite
concentrate and red mud does not reach the melting
temperature and does not melt, and when heating within the
above range, it is possible to adjust the composition of components of alumina and silica in the produced slag, and to physically separate the reduced iron component.
The above heating can be performed in any one selected
from the group consisting of a sintering furnace, a rotary
furnace and an arc furnace.
When using a sintering furnace (sinter bed) or a rotary
furnace (rotary kiln), it is possible to easily heat to a
setting temperature by adding a carbon source, and it is
very advantageous to adjust the reaction temperature and
reaction time during progressing the reducing reaction by
heating.
When the heating is carried out in an arc furnace, the
temperature can rapidly increase to a reduction temperature
of 2000 °C and the weight of the reduced iron increase to
allow gravity separation.
The above reduced iron can be formed in a molten droplet
shape.
When ilmenite concentrate and red mud are mixed and
heated, iron of the iron oxide component in ilmenite
concentrate and the iron oxide contained in red mud is
reduced and discharged, and at this time, discharged in a
molten droplet shape.
It is possible to separate iron components by a single
process using ilmenite concentrate and red mud, and the
reduced iron can be easily sorted by a physical method and
its recycling is possible.
The molten droplets are physically separated to remove iron and recover titanium dioxide slag in step F300.
When the reduced iron is formed in a molten droplet
shape, iron components are agglomerated and easily
attracted to magnetism, and iron components in ilmenite
concentrate and red mud can be together separated by one
process through a magnetic separation.
The molten droplet is contained in 25 to 30% by weight
in the reduced material.
The weight of the molten droplet can be increased
through steps for heating and reducing.
Also, when reduced in an arc furnace, the weight of iron
is increased to allow gravity separation.
In the titanium dioxide slag, iron is separated and
removed and the content of titanium dioxide issued from
ilmenite concentrate and red mud is increased, and thus the
quality of titanium dioxide to be recovered is very
improved.
The titanium dioxide slag is introduced into a Bayer
process to recover alumina (A1 2 0 3 ) in step F400.
The Bayer process refers to a process of discharging
alumina as crystals by adding caustic soda and leaching
under the condition of a high temperature and a high
pressure.
The titanium dioxide slag may contain alumina and silica
derived from red mud.
In case that the alumina and silica are not removed, the
quality of the recovered titanium dioxide may be lowered.
In the Bayer process, caustic soda (NaOH) may be added
to a titanium dioxide slag and alumina may be leached at
150 to 200 °C at a pressure of 15 to 20 bar.
It is possible to recover alumina by the above alkaline
leaching with caustic soda at the above high temperature
and high pressure range. In case of not reaching the above
temperature and pressure range, the leaching efficiency of
alumina is decreased.
The Beyer process can leach alumina by adding from 1.25
to 6.25 M of caustic soda (NaOH) to a titanium dioxide slag.
Within the above concentration range, alumina may be and
precipitated, and silica contained in titanium dioxide slag
may be dissolved and leached together.
In case that the caustic soda is less than 1.25 M, it is
difficult to contain alumina to less than 3% by weight in
the titanium dioxide slag recovered.
By adjusting the concentration of caustic soda to
control the content of alumina and silica in the titanium
dioxide slag, it is possible to recover titanium dioxide
with a high quality.
Thereafter, the titanium dioxide slag in which alumina
was separated is subjected to acid leaching to remove
silica (SiO 2 ) in step F500.
The acid-leaching can remove silica in the titanium
dioxide slag by using from 0.05% to 30% of sulfuric acid
and leaching for 5 minutes to 10 hours.
The concentration of sulfuric acid can vary depending on
the nature of the residue and can be selected on the
relation of inverse proportion to the leaching time.
In the acid-leaching step, all iron components in the
residue can be removed, and simultaneously, silica remained
in the titanium dioxide slag can also be removed together.
Through the above acid-leaching, all of the gangue
component and impurities in the titanium dioxide slag can
be removed, and the quality of the final product of
titanium dioxide slag is greatly improved by removing the
remaining iron and silica.
The titanium dioxide slag recovered may have a quality
of 70% to 97%.
The above titanium dioxide slag is used as a high
quality titanium dioxide raw material such as pigment or
the like.
In the smelting method according to another embodiment
of the present disclosure, therefore, alumina (A12 0 3 )
contained in red mud is separated and reused as well as the
quality of titanium dioxide remained can be greatly improve
by removing alumina and silica together with iron
impurities.
Hereinafter, preferred examples are provided to help
understanding of the present disclosure, but the following
examples are merely to illustrate the present disclosure,
and the scope of the present disclosure is not limited to the following examples.
<Example 1> Recovery of titanium dioxide via aeration
and acid leaching
A mixture of ilmenite concentrate 100 g and red mud 100
g was pressed to prepare briquettes.
Powdered ilmenite concentrate and red mud were uniformly
mixed through a ball mill and then briquetted using a
pelletizer with a pressure of 5 tons at maximum.
A bituminous coal was added to the briquettes, which
were heated to 1450 °C in a rotary furnace.
It was confirmed that a high-temperature melt occurred
and the resulting molten droplets and residues were
identified.
The molten droplets were separated using a magnetic
separator. The residue was subjected to aeration by
introducing air and to acid leaching by introducing
sulfuric acid with a concentration of 30%.
The quality of recovered titanium dioxide was determined.
<Example 2> Recovery of titanium dioxide according to
Beyer process
FIG. 5 is a schematic diagram showing the configuration
of the method of smelting ilmenite using red mud according
to another embodiment of the present disclosure.
Referring to FIG. 5, a mixture of ilmenite concentrate
100 g and red mud 100 g was pressed to prepare briquettes.
Powdered ilmenite concentrate and red mud were uniformly
mixed through a ball mill and then briquetted using a
pelletizer with a pressure of 5 tons at maximum.
Bituminous coal was added to the briquettes, which were
reduced by heating to 2000 °C for 15 minutes in an arc
furnace.
It was confirmed that a high-temperature melt occurred
and the resulting molten droplets and residues were
identified.
The molten droplets were separated using a magnetic
separator.
The molten droplets were removed to recover the titanium
dioxide slag.
FIG. 6 is a photograph of a high temperature and high
pressure leaching apparatus.
Referring FIG. 6, in the high temperature and high
pressure leaching apparatus was charged caustic soda
together with titanium dioxide slag from which molten
droplets were removed and a leaching was made under a
condition of 200 0C and 20 bar for 1 hour.
After leaching, leached components were analyzed to
determine the content of alumina and silica in the titanium
dioxide slag.
An acid-leaching was made by adding sulfuric acid at a
concentration of 30% to titanium dioxide slag from which
alumina was removed.
The quality of the finally-recovered titanium dioxide slag was determined.
<Experiment 1> Remove of iron by reduction
FIG. 3 is a photograph of ilmenite, red mud and free
burning coal samples which are starting materials in the
method of smelting ilmenite using red mud according to an
embodiment of the present disclosure.
FIG. 4 is a photograph showing molten droplets of iron
reduced by heating in the method of smelting ilmenite using
red mud according to an embodiment of the present
disclosure.
[Table 1]
Composition SiO 2 A1 2 0 3 FeOx CaO MgO Na20 TiO 2 MnO Sample 12.8 Ilmenite 1.06 1.10 (Fe O 3 ) 0.59 0.35 - 49.5 1.0 31.62 (FeO)
Red mud 10.0 23.1 37.4 6.0 0.3 5.3 7.9 0.1 (Fe 2 0 3 )
Table 1 shows the results that the components of
ilmenite concentrate and red mud, which are starting
materials according to Examples of the present disclosure,
were analyzed by the energy dispersive X-ray fluorescence
analysis. Referring to Table 1, it is confirmed that
ilmenite concentrate and red mud contain the titanium
dioxide component and the iron component which are needed for the separation and recovery.
[Table 2]
Composition SiO2 A1 2 0 3 FeOx CaO MgO Na20 TiO MnO 2 Sample Titanium 1.97 dioxide slag 7.01 1.81 (Fe 2 O 3 ) 0.59 0.35 - 81.8 1.0 after 8.84 reduction (FeO) Molten oxide 11.5 2.14 14.4 5.5 0.5 5.0 45.2 1.5
Table 2 shows the components of titanium dioxide slag
after the melting and reducing step through heating.
Referring to Table 2, all components of iron oxide (FeOx)
in the slag after the reduction were determined to be a
very little amount of less than 10% compared to the red mud
and ilmenite introduced, and thus it is confirmed that the
reduction reaction proceeded very effectively.
Also, due to magnetic separation, the iron component
greatly decreased and the content of titanium dioxide
greatly increased in the titanium dioxide slag after
reduction.
In the production process of titanium dioxide, when
mixing ilmenite and red mud, heating with a free-burning
coal in a rotary furnace and adjusting the reaction
temperature, the iron reacted with the free-burning coal
again becomes a strong reducing agent and reduces most of
iron component to produce molten droplets.
Therefore, since the method of smelting ilmenite utilizing red mud according to the present disclosure utilizes red mud which is waste difficult to treat, it is possible to obtain a high-quality titanium dioxide by smelting a low-quality ilmenite in an environmentally friendly manner.
<Experiment 2> Leaching of alumina and silica according
to Beyer process
It was confirmed whether the impurities alumina and
silica could be removed from a titanium dioxide slag, in
which iron component was reduced and removed by magnetic
separation of molten droplets, by adding caustic soda and
leaching under a high temperature and high pressure.
There is a problem that red mud contains alumina and
silica in addition to iron oxide and they remain after
magnetic separation after reduction, therby to increase the
load of an acid leaching process and to decrease the
quality of titanium dioxide recovered.
7 is a graph showing alumina and silica contents
depending on caustic soda concentration in the Bayer
process step in the method of smelting ilmenite using red
mud according to another embodiment of the present
disclosure.
Referring to FIG. 7, it was confirmed that alumina as
well as silica remaining in titanium dioxide slag were
removed when the concentration of caustic soda is 2.5 M or
higher in case of leaching under the condition of 200 °C and 20 bar for 1 hour.
In particular, when the concentration of caustic soda is
2.5 M or higher, the content of alumina and silica can be
effectively controlled to 3% by weight or less.
Therefore, the method of smelting ilmenite using red mud
according to an embodiment of the present disclosure can
separate and efficiently recover iron component and
titanium dioxide component by using red mud.
Also, the method of smelting ilmenite using red mud
according to another embodiment of the present disclosure
can utilize red mud which is waste difficult to treat and
obtain a variety of by-products, which can be recycled.
In the production process of titanium dioxide, when
mixing ilmenite and red mud, heating with a free-burning
coal in a rotary furnace and adjusting the reaction
temperature, the iron reacted with the free-burning coal
again becomes a strong reducing agent and reduces most of
iron component to produce molten droplets.
Therefore, since the method of smelting ilmenite
utilizing red mud according to the present disclosure
utilizes red mud which is waste difficult to treat, it is
possible to obtain a high-quality titanium dioxide by
smelting a low-quality ilmenite in an environmentally
friendly manner.
At this time, if decreasing iron component with a method
of separating molten droplets by a magnetic separation, it
is possible to obtain a high-quality of titanium dioxide by separating iron component, while decreasing the load of acid-leaching process.
Also, when alumina and silica contained in red mud are
concentrated in the reduced titanium dioxide slag, the
impurities alumina as well as silica can be removed by
introducing into Beyer process and leaching under a high
temperature and a high pressure. The alumina to be
discharged in crystal may be recovered and reused.
Although specific embodiments of the method of smelting
titanium dioxide using ilmenite according to the present
disclosure have been described so far, it is apparent that
various modifications can be made without departing from
the scope of the present disclosure.
Therefore, the scope of the present disclosure should
not be limited to the embodiments described, but should be
defined by the claims below and equivalents thereof.
In other words, it should be understood that the
foregoing embodiments are in all respects as illustrative
and not restrictive, and it should be interpreted that the
scope of the disclosure is presented by the following
claims rather than the detailed description, and that all
changes or modifications derived from the meaning and scope
of the claims and its equivalent concept should be included
in the scope of the present disclosure.
Claims (25)
1. A method for smelting ilmenite using red mud, comprising
the steps of:
(a) mixing an ilmenite concentrate and red mud to form a
mixture;
(b) adding a carbon source to the mixture, followed by
heating to reduce iron in the mixture;
(c) separating reduced iron through a magnetic separation;
and
(d) subjecting residue to aeration and acid-leaching to
remove iron in the residue and recover titanium dioxide,
wherein said red mud is added from 10 to 200 parts by
weight based on a total of 100 parts by weight of the ilmenite
concentrate,
wherein, in the step of mixing an ilmenite concentrate and
red mud to form a mixture, the mixture is pressurized to form
a briquette, and
wherein, in the step of adding a carbon source to the
mixture, iron oxide contained in the red mud changes to
reduced iron.
2. The method according to claim 1, characterized in that
said ilmenite concentrate contains titanium dioxide (TiO 2 )
in 17 to 50 % by weight.
3. The method according to claim 1 or claim 2, characterized
in that
said red mud contains titanium dioxide (TiO 2 ) in 5 to 10 %
by weight.
4. The method according to any one of claims 1 to 3,
characterized in that
said carbon source is any one selected from free-burning
coals consisting of peat, brown coal and bituminous coal.
5. The method according to any one of claims 1 to 4,
characterized in that
said carbon source is added from 10 to 100 parts by weight
based on a total of 100 parts by weight of the mixture.
6. The method according to any one of claims 1 to 5,
characterized in that
said carbon source is added to the mixture,
followed by heating at 1350 to 1500 °C for 8 hours to 12
hours to reduce the iron in the mixture.
7. The method according to any one of claims 1 to 6,
characterized in that
said heating is performed in a sintering furnace or a
rotary furnace.
8. The method according to any one of claims 1 to 7,
characterized in that
said reduced iron is formed in a molten droplet form, which
is physically separated through a magnetic force sorting.
9. The method according to any one of claims 1 to 8,
characterized in that
said residue is subjected to aeration by introducing air for 30 minutes to 30 hours.
10. The method according to any one of claims 1 to 9,
characterized in that
said acid leaching is performed by using 0.05 to 30 % of
sulfuric acid and leaching for 5 minutes to 10 hours to remove
iron in the residue.
11. The method according to any one of claims 1 to 10,
characterized in that
said recovered titanium dioxide has a quality of 88% to 95%.
12. A method for smelting ilmenite using red mud, comprising
the steps of:
(i) mixing an ilmenite concentrate and red mud to form a
mixture;
(ii) adding a carbon source to the mixture, followed by
heating to reduce iron in the mixture to form molten droplets;
(iii) physically separating the molten droplets to remove
the iron and recover a titanium dioxide slag;
(iv) introducing the titanium dioxide slag into a Bayer
process to recover alumina (A1 2 0 3 ); and
(v) subjecting the alumina-separated titanium dioxide slag
to acid-leaching to remove silica (SiO2 );
wherein said Bayer process is performed by adding 1.25 to
6.25M of caustic soda (NaOH) to titanium dioxide slag to leach
alumina,
wherein, in the step of mixing an ilmenite concentrate and
red mud to form a mixture, the mixture is pressurized to form
a briquette, and wherein, in the step of adding a carbon source to the mixture, iron oxide contained in the red mud changes to reduced iron.
13. The method according to claim 12, characterized in that
said ilmenite concentrate contains titanium dioxide (TiO 2
) from 17 to 50 % by weight.
14. The method according to claim 12 or claim 13,
characterized in that
said red mud comprises titanium dioxide (TiO 2 ), alumina
(A12 0 3 ) and silica (SiO 2 ) .
15. The method according to claim 14, characterized in that
said titanium dioxide is contained from 5 to 10 % by weight.
16. The method according to any one of claims 12 to 15,
characterized in that
red mud is added from 10 to 200 parts by weight for a total
of 100 parts by weight of said ilmenite concentrate.
17. The method according to any one of claims 12 to 16,
characterized in that
said carbon source is any one selected from free-burning
coals consisting of peat, brown coal and bituminous coal.
18. The method according to any one of claims 12 to 17,
characterized in that
said carbon source is added from 10 to 100 parts by weight
for total 100 parts by weight of said mixture.
19. The method according to any one of claims 12 to 18,
characterized in that
the carbon source is added to said mixture,
followed by heating at 1400 to 2000 °C for 15 minutes to 10
hours to reduce iron in the mixture.
20. The method according to any one of claims 12 to 19,
said heating is performed in any one selected from a group
consisting of a sintering furnace, a rotary furnace and an arc
furnace.
21. The method according to any one of claims 12 to 20,
characterized in that
said iron is reduced and formed in a molten droplet form,
which is physically separated through a magnetic force sorting
or a gravity sorting.
22. The method according to any one of claims 12 to 20,
characterized in that
said molten droplet is contained from 25 to 30 % by weight
in said reduced matter.
23. The method according to any one of claims 12 to 22,
characterized in that
said Bayer process is performed by adding caustic soda
(NaOH) to titanium dioxide slag and leaching alumina at 150 to
2000C and at a pressure of 15 to 20 bar.
24. The method according to any one of claims 12 to 23, characterized in that said acid leaching is performed by using 0.05 to 30 % of sulfuric acid and leaching for 5 minutes to 10 hours to remove iron together with silica remaining in titanium dioxide slag.
25. The method according to any one of claims 12 to 24,
characterized in that
said recovered titanium dioxide has a quality of 70% to 97%.
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| KR1020170050662A KR101790128B1 (en) | 2017-04-19 | 2017-04-19 | Smelting method of titanium dioxide using ilmenite concentrate |
| KR10-2017-0050662 | 2017-04-19 | ||
| KR10-2018-0041532 | 2018-04-10 | ||
| KR1020180041532A KR101900672B1 (en) | 2018-04-10 | 2018-04-10 | Smelting method of ilmenite concentrate using Red mud |
| PCT/KR2018/004563 WO2018194397A1 (en) | 2017-04-19 | 2018-04-19 | Method for smelting ilmenite using red mud |
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| CA3244282A1 (en) * | 2021-02-16 | 2022-08-25 | Gron Metallic Group, Inc. | Process for recovering metals and oxides from iron-containing tailings |
| CN115301400B (en) * | 2022-08-05 | 2023-11-07 | 中国地质科学院矿产综合利用研究所 | System and method for beneficiation of ultrafine ilmenite |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR0160753B1 (en) * | 1990-05-24 | 1998-11-16 | 마이클 존 홀리트 | Production of acid soluble titania |
| CN102766715A (en) * | 2012-07-27 | 2012-11-07 | 胡长春 | Slag-free production process of ilmenite |
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|---|---|---|---|---|
| CA2226842A1 (en) * | 1995-07-11 | 1997-01-30 | Comalco Aluminium Limited | High yield precipitation process |
| GB0313886D0 (en) * | 2003-06-16 | 2003-07-23 | Jha Animesh | Extraction route for Ti02 and alumina from bauxite and bauxitic residues,and titaniferrous deposits and wastes |
| AU2011272918B2 (en) * | 2010-06-30 | 2014-07-31 | Gharda Medical and Advanced Technologies Foundation | Process for extracting metals from aluminoferrous titanoferrous ores and residues |
| KR101790128B1 (en) * | 2017-04-19 | 2017-10-26 | 한국지질자원연구원 | Smelting method of titanium dioxide using ilmenite concentrate |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR0160753B1 (en) * | 1990-05-24 | 1998-11-16 | 마이클 존 홀리트 | Production of acid soluble titania |
| CN102766715A (en) * | 2012-07-27 | 2012-11-07 | 胡长春 | Slag-free production process of ilmenite |
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