U.S. patent application number 13/087787 was filed with the patent office on 2012-05-24 for method of fixing carbon dioxide comprising a step of recycling the used extraction solvent.
This patent application is currently assigned to KIA MOTORS CORPORATION. Invention is credited to Sung Yeup Chung, Ki Chun Lee.
Application Number | 20120128553 13/087787 |
Document ID | / |
Family ID | 46021474 |
Filed Date | 2012-05-24 |
United States Patent
Application |
20120128553 |
Kind Code |
A1 |
Chung; Sung Yeup ; et
al. |
May 24, 2012 |
METHOD OF FIXING CARBON DIOXIDE COMPRISING A STEP OF RECYCLING THE
USED EXTRACTION SOLVENT
Abstract
A method of fixing carbon dioxide is provided. After metal ion
components are extracted from natural mineral or steel slag through
acid treatment, carbon dioxide is injected to fix carbon dioxide by
carbonating the same. Since the procedure of pH adjustment is
unnecessary, the reaction is carried out effectively, and a
continuous process is enabled. Further, since the used extraction
solvent is recycled, the cost of fixing carbon dioxide is reduced.
The disclosed method of fixing carbon dioxide enables effective
removal of carbon dioxide produced from the steelmaking industry,
thereby significantly reducing greenhouse gas emission and allowing
recycling of the conventionally discarded steel slag.
Inventors: |
Chung; Sung Yeup; (Seoul,
KR) ; Lee; Ki Chun; (Seoul, KR) |
Assignee: |
KIA MOTORS CORPORATION
Seoul
KR
HYUNDAI MOTOR COMPANY
Seoul
KR
|
Family ID: |
46021474 |
Appl. No.: |
13/087787 |
Filed: |
April 15, 2011 |
Current U.S.
Class: |
423/1 |
Current CPC
Class: |
C01B 32/60 20170801;
C22B 7/04 20130101; Y02P 10/212 20151101; Y02P 10/20 20151101 |
Class at
Publication: |
423/1 |
International
Class: |
C22B 3/44 20060101
C22B003/44 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 24, 2010 |
KR |
10-2010-0117700 |
Claims
1. A method of fixing carbon dioxide comprising the steps of: (a)
treating natural mineral or steel slag with an acid to extract
metal ion components, thereby providing an extraction solution
containing the metal ion components; (b) injecting carbon dioxide
into the extraction solution containing the resulting metal ion
components to carbonate the same, thereby providing a solution in
which resulting carbonates are dissolved; (c) transferring the
solution in which the resulting carbonates are dissolved to a
dissolved carbonate storage tank; (d) transferring the solution
from the dissolved carbonate storage tank to a carbonate
separation/purification tank, and adjusting pH to 7 or above to
separate the carbonates; (e) treating the solution from which the
carbonates have been separated with an acid; and (f) recycling the
treated solution to step (a) as an extraction acid.
2. The method of fixing carbon dioxide according to claim 1,
wherein said treating with the acid in step (e) is performed at
about pH 3-5.
3. The method of fixing carbon dioxide according to claim 1,
wherein said carbonating is performed at normal temperature under
normal pressure.
4. The method of fixing carbon dioxide according to claim 1,
wherein step (e) comprises adjusting pH to about 3-5 using one or
more acid(s) selected from a group consisting of formic acid,
acetic acid, propionic acid, phosphoric acid, phosphorous acid,
citric acid and oxalic acid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.119
to Korean Patent Application No. 10-2010-0117700, filed on Nov. 24,
2010, in the Korean Intellectual Property Office, the disclosure of
which is incorporated herein by reference in its entirety.
BACKGROUND
[0002] (a) Technical Field
[0003] The present invention relates to a method of fixing carbon
dioxide. More particularly, the present invention relates to a
method for fixing carbon dioxide utilizing natural mineral or steel
slag, thereby reducing emission of carbon dioxide into the
atmosphere.
[0004] (b) Background Art
[0005] Global carbon dioxide emissions have been rapidly increasing
due to increased fossil fuel consumption. Carbon dioxide emissions
have been recently recognized as the main cause of global warming,
and thus, countries around the world are making efforts to provide
appropriate regulations to reduce such emissions.
[0006] The reduction in carbon dioxide emissions can be
accomplished by reducing the use of fossil fuel itself, or by a
method wherein the carbon dioxide produced by the use of fossil
fuel is separated, collected and fixed. The separated and collected
carbon dioxide can, for example, be used as a source for methanol
synthesis. The separated and collected carbon dioxide can also be
fixed by dumping it into the ocean or by using carbonate
minerals.
[0007] According to one method, carbon dioxide emitted from plants
is fixed using carbonate minerals. In particular, the carbon
dioxide is reacted with alkaline substances (e.g. CaO, MgO,
K.sub.2O, Na.sub.2O, etc.) existing in minerals to produce
carbonates (e.g. CaCO.sub.3, MgCO.sub.3, Na.sub.2CO.sub.3,
K.sub.2CO.sub.3, etc.).
[0008] Slags produced from steelmaking processes include molten
iron pretreatment slag, converter slag, stainless steel slag,
electric furnace slag, and the like. These steel slags are mostly
buried, with a limited amount being utilized as cement or
aggregates for road or building construction. Various other methods
for utilizing the discarded steel slag are desired and have been
proposed, particularly as it becomes more difficult to find
landfills in which to bury the slag.
[0009] Korean Patent Application Publication No. 2002-0050429
proposes a method of fixing carbon dioxide on the surface of steel
slag for use in harbor construction or artificial fish banks for
fish. Korean Patent Application Publication No. 2006-0023206
proposes fixing carbon dioxide on the surface of slag containing a
certain level of water by reacting it with carbon dioxide. However,
these two methods require an excessive reaction time since the
efficiency of the reaction between carbon dioxide and slag is very
low. Thus, the methods are economically impractical.
[0010] Korean Patent No. 0891551 (Application No. 2008-0025573)
proposes a method of solidifying carbon dioxide by carbonating
alkaline components extracted from steel slag with gaseous carbon
dioxide through either a pressurized or a normal-pressure
hydrothermal reaction. However, the hydrothermal reaction consumes
a great deal of energy, and it is unclear how the carbon dioxide
can be fixed following the carbonation of the alkaline
components.
[0011] Korean Patent No. 0801542 (Application No. 2006-0105753)
proposes a method of fixing carbon dioxide using natural mineral
talc. However, according to this method the particles must be 125
.mu.m or less, thus requiring excessive energy for the
pulverization of mineral. Further, after the alkaline components
are treated with a weak acid solvent, such as acetic acid, for
extraction, the pH is increased to fix the carbon dioxide through
carbonation. This increase in pH causes some metal ions (e.g.,
Ca.sup.2+) to react with hydroxide ions (OH.sup.-) to form milky
lime (Ca(OH).sub.2), resulting in suspension. Thus, an additional
precipitation or filtration procedure is required. Since the
precipitated carbonate is suspended in the solution, the separation
is difficult and it is difficult to establish an industrially
applicable continuous process.
SUMMARY
[0012] The present invention provides to a method for effectively
fixing carbon dioxide that overcomes the problems with conventional
methods. The present method is applicable to actual processes,
whereby carbon dioxide can be fixed via liquid-phase reaction. The
present method further provides improved reaction efficiency, at
normal temperature under normal pressure, thus reducing energy
consumption. Further, according to the present methods, it is
unnecessary to adjust pH for carbon dioxide fixation, thus
preventing the formation of suspended milky lime and allowing for a
continuous process.
[0013] According to further embodiments, the present invention
provides a method capable of lowering the cost of fixing carbon
dioxide by recycling the used extraction solution after the
separation of carbonates.
[0014] In a general aspect, the present invention provides a method
of fixing carbon dioxide comprising: (a) treating natural mineral
or steel slag with an acid to extract metal ion components; (b)
injecting carbon dioxide into an extraction solution containing the
metal ion components obtained in step (a) to carbonate the same;
(c) transferring a solution in which carbonates resulting from step
(b) are dissolved to a dissolved carbonate storage tank and storing
the same; (d) transferring the stored dissolved carbonates to a
carbonate separation/purification tank and adjusting pH to 7 or
above to separate the carbonates; and (e) treating the solution
from which the carbonates have been separated with an acid, and
recycling the treated solution as the extraction solvent (acid) in
step (a).
[0015] The above and other aspects and features of the present
invention will be described infra.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and other objects, features and advantages of the
present invention will now be described in detail with reference to
certain exemplary embodiments thereof illustrated in the
accompanying drawings which are given hereinbelow by way of
illustration only, and thus are not limitative of the disclosure,
and wherein:
[0017] FIG. 1 shows an existing process of fixing carbon dioxide
using slag; and
[0018] FIG. 2 shows a method of fixing carbon dioxide using natural
mineral or steel slag according to the present invention.
[0019] It should be understood that the appended drawings are not
necessarily to scale, presenting a somewhat simplified
representation of various preferred features illustrative of the
basic principles of the disclosure. The specific design features of
the disclosure as disclosed herein, including, for example,
specific dimensions, orientations, locations and shapes, will be
determined in part by the particular intended application and use
environment.
DETAILED DESCRIPTION
[0020] Hereinafter, reference will now be made in detail to various
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings and described below. While
the disclosure will be described in conjunction with exemplary
embodiments, it will be understood that the present description is
not intended to limit the disclosure to those exemplary
embodiments. On the contrary, the disclosure is intended to cover
not only the exemplary embodiments, but also various alternatives,
modifications, equivalents and other embodiments, which may be
included within the spirit and scope of the disclosure as defined
by the appended claims.
[0021] The present invention provides a method of fixing carbon
dioxide comprising:
[0022] (a) treating natural mineral or steel slag with an acid to
extract metal ion components;
[0023] (b) injecting carbon dioxide into an extraction solution
containing the metal ion components obtained in step (a) to
carbonate the same;
[0024] (c) transferring the solution of step (b), in which
carbonates resulting from step (b) are dissolved, to a dissolved
carbonate storage tank and storing the same;
[0025] (d) transferring the stored dissolved carbonates to a
carbonate separation/purification tank and adjusting pH to 7 or
above to separate the carbonates; and
[0026] (e) treating the solution from which the carbonates have
been separated (in from step (d)) with an acid, and recycling the
acid treated solution for use as the extraction solvent (acid) in
step (a).
[0027] In step (a), the natural mineral is not particularly
limited. For example, peridotite, basalt, talc, serpentinite,
wollastonite, etc., which contain a large amount of metal oxides,
such as calcium oxide and/or magnesium oxide, may be used. The
contents of calcium oxide and magnesium oxide in serpentinite and
wollastonite are shown, for example, in Table 1.
[0028] In step (a), the steel slag may be selected from, but is not
limited to, slag, electric furnace slag or converter slag produced
from, for example, an ironworks during blast furnace, converter or
oxygen blowing processes. Currently, steel slag is mostly utilized
as cement or aggregates for road or building construction. The
chemical composition of various steel slag is also shown in Table
1.
TABLE-US-00001 TABLE 1 CaO (wt %) MgO (wt %) Natural mineral
Serpentinite 0 40 Wollastonite 48 0 Steel slag Blast furnace slag
41 10 Converter slag 46 2 Electric furnace slag 20 5 Ladle furnace
slag 54 10
[0029] Since the natural mineral and the steel slag contain a large
amount of metal oxides, including calcium oxide and magnesium
oxide, they exhibit high basicity. As such, upon acid treatment,
the metal components of the metal oxides are released into the
solution, thus exhibiting alkaline property. Generally, these metal
ion components are mostly Ca.sup.2 and Mg.sup.2+, and the remainder
may be, for example, K.sup.+, Na.sup.+, etc.
[0030] In accordance with some embodiments, the acid treatment may
be performed at about pH 3-5. To provide the desired pH, an acidic
substance such as acetic acid, sodium acetate, hydrochloric acid,
etc., may be used at a suitable concentration.
[0031] Upon acid treatment, the solution containing the metal ions,
e.g., Ca.sup.2+, Mg.sup.2+, etc., is provided with an acidic
pH.
[0032] According to the conventional methods for fixing by
carbonation, the pH of the extraction solution is adjusted to about
12, followed by injection of carbon dioxide to form a carbonate
precipitate. During this procedure, some of the dissolved metal
ions (e.g., Ca.sup.2+, Mg.sup.2+, etc.) react with hydroxide ions
(OH.sup.-) to form milky lime, thus resulting in suspension. Unless
the suspending solid is effectively separated, it becomes difficult
to fix carbon dioxide through a continuous process. As a result,
treatment of carbon dioxide on a large scale is very difficult, if
not impossible.
[0033] In accordance with the present invention, the procedure of
adjusting the pH to about 12 is omitted and, thus, this limitation
is overcome. In particular, by omitting the pH adjustment
procedure, the present invention avoids the formation of milky lime
and, consequently, the formation of suspending solids. Thus, the
present invention allows for a continuous process, and treatment of
carbon dioxide on a large scale is possible. According to the
present invention, the procedure for adjusting pH to an alkaline
range (pH 7 or above) for separation of the carbonates is carried
out after the CO2 reaction with metal ion components is completed.
Since the metal ions have participated in reactions to form the
carbonates, there is very little possibility that they will form
suspending solids through reaction with hydroxide ions. The
solution in which the carbonates (i.e. the carbonates resulting
from the step (b) carbon dioxide fixing) are dissolved is then
transferred to a dissolved carbonate storage tank and for storage.
Subsequently, the stored dissolved carbonate solution is
transferred to a carbonate separation/purification tank, and the pH
of the solution is adjusted to 7 or above to separate the
carbonates. Consequently, the procedures of carbonation and
carbonate separation can be performed continuously.
[0034] In embodiments of the present invention, the carbonation in
step (b) may be performed at normal temperature under normal
pressure. As referred to herein, "normal temperature" and "normal
pressure" mean that no additional heat or pressure needs to be
applied. For example, the temperature may be about 0-40.degree. C.,
and in accordance with some embodiments about 10-25.degree. C., and
the pressure may be about 0.1-5 atm, and in accordance with some
embodiments about 0.5-2 atm. In accordance with the present
invention, the carbonation can be completed within 5 minutes
without requiring an energy-consuming hydrothermal reaction.
According to some embodiments, the rate of injection of the carbon
dioxide in step (b) can be controlled so as to provide a desired
time for completion of carbonation. In particular, according to
various embodiments, the carbonation reaction of step (b) can be
completed within 5 minutes when the injection rate of carbon
dioxide is about 2 L/min. Further, since the release of the metal
ion components in step (a) can be accomplished within 2 hours, the
overall process can be completed in about 2 hours, making it a very
economical process. Thus, carbon dioxide can be effectively fixed
using natural mineral or steel slag (e.g., slag, electric furnace
slag or converter slag produced from an ironworks during blast
furnace, converter or oxygen blowing processes), thereby remarkably
reducing the emission of greenhouse gas and allowing the
utilization of the previously discarded steel slag.
[0035] The carbon dioxide gas treated by the method according to
the present invention may be any carbon dioxide gas, including
those produced as by-products from industrial furnaces such as
blast furnaces, lime burning furnaces, coking furnaces, etc.,
sintering or hot-rolling processes, power generation, waste heat
boilers, and the like. Accordingly, if an ironworks is equipped
with a facility capable of fixing carbon dioxide generated in the
steelmaking process, the steel slag produced during the process may
be utilized to fix the global warming-causing gas on site. Through
this, environmental regulations can be met, and by-products such as
metal oxides can be utilized as a new source of revenue, rather
than waste.
[0036] According to the present invention, the solution with the
carbonates separated in step (d) is not discarded but can be
recycled as the extraction solvent (also referred to as "acid") in
step (a). Since the solution resulting from step (d) has a pH of 7
or above, it is first treated with an acid to adjust pH to 3-5 for
subsequent use as the extraction solvent in step (a). The acid
treatment may be carried out using one or more acid(s) preferably
selected from a group consisting of formic acid, acetic acid,
propionic acid, phosphoric acid, phosphorous acid, citric acid and
oxalic acid. The recycled extraction solvent can be mixed with a
fresh extraction solvent. and the mixture supplied to the
extracting device (as shown, for example, in FIG. 2). By recycling
the extraction solution, the cost related to preparation,
purification and disposal of the extraction solution is reduced,
and the overall cost of carbon dioxide fixing can be reduced
significantly.
[0037] In accordance with the present invention, a method is
provided whereby carbon dioxide is fixed by carbonation without pH
adjustment, and whereby high-purity carbonate can be prepared in
about 2 hours. Further, since a continuous process is enabled by
the present method, treatment of carbon dioxide in large scale is
possible. In addition, since the extraction solution can be
recycled, the cost related to preparation, purification and
disposal of the extraction solution can be reduced and the overall
cost of carbon dioxide fixing can be reduced significantly.
[0038] The method of fixing carbon dioxide according to the present
invention, whereby metal ions are extracted through acid treatment
of natural mineral or steel slag, is much more effective than the
existing solid-gas reaction methods. Since the reaction is carried
out at normal temperature under normal pressure, without requiring
an energy-intensive procedure such as hydrothermal synthesis,
energy consumption can be reduced. Further, since the pH adjustment
for fixing carbon dioxide is omitted, formation of suspended milky
lime can be prevented, and a continuous process is enabled.
Further, since the extraction solution can be recycled, the cost
related to preparation, purification and disposal of the extraction
solution can be reduced and the overall cost of carbon dioxide
fixing can be reduced significantly.
[0039] Since the method of fixing carbon dioxide according to the
present invention allows reduction of carbon dioxide emissions
using steel slag, which is currently used only for valueless
applications, it can be an effective measure to cope with the
greenhouse gas reduction requirement imposed on steelmaking
companies, while allowing for recycling of the discarded steel slag
as carbonate.
[0040] In addition, it is noted that the cost related to
preparation, purification and disposal of the extraction solution
used in a carbon dioxide fixing process accounts for more than 50%
of the total cost of fixing carbon dioxide. Thus, according to the
present invention, the overall cost of carbon dioxide fixing is
reduced by reducing the cost related to preparation, purification
and disposal of the extraction solution. Further, the net amount of
fixed carbon dioxide can be enhanced as the amount of the used
extraction solution is decreased.
[0041] The present invention has been described in detail with
reference to specific embodiments thereof. However, it will be
appreciated by those skilled in the art that various changes and
modifications may be made in these embodiments without departing
from the principles and spirit of the disclosure, the scope of
which is defined in the appended claims and their equivalents.
* * * * *