KR101450697B1 - A storage method of carbon dioxide using indirect carbonation of cement kiln dust - Google Patents

Abstract

The present invention relates to a cement kiln dust (CKD) which is produced as a by-product in the cement industry and increases the conversion rate to calcium carbonate (CaCO ₃ ) which is a stable mineral state by using carbon dioxide, The present invention relates to a method for storing carbon dioxide by indirect carbonation treatment of kiln dust, and it is advantageous that CKD for storing carbon dioxide can be stably secured as a by-product from the cement industry and used as a raw material for mineral carbonation having high carbonation efficiency . Also, since the high purity calcium carbonate produced according to the present invention is widely used in various industrial fields, it is expected to have high economic value by recycling and additionally economical efficiency in the implementation of carbon emission trading system.

Description

[0001] The present invention relates to a method for storing carbon dioxide by indirect carbonation treatment of a cement kiln dust,

The present invention relates to a cement kiln dust (CKD) which is produced as a by-product in the cement industry and increases the conversion rate to calcium carbonate (CaCO ₃ ) which is a stable mineral state by using carbon dioxide, The present invention relates to a method for indirectly carbonating a kiln dust to store carbon dioxide.

Excessive emission of greenhouse gases due to the development of industry has been pointed out as the main cause of warming beyond the allowable range of nature. A greenhouse gas species is carbon dioxide (CO _2), methane (CH _4), and the like, Asan per nitrogen (N ₂ O), chlorofluorocarbons (CFCs), ozone (O ₃₎ is carbon dioxide, which account for about 80% of the double representative It is greenhouse gas. The amount of carbon dioxide emitted is steadily increasing. As the current rate increases, the average global temperature will rise by about 0.8 ~ 3.5 ℃ until 2100, and climate change, ecosystem disturbance, sea level rise, soil erosion (See Non-Patent Document 1).

As the 2005 Kyoto Protocol became officially in force, regulations on carbon dioxide emissions were strengthened and 38 countries, including the US, Japan, and the EU, should reduce their greenhouse gas emissions by an average of 5% Korea is also subject to obligatory reduction from 2013, and it is required to actively cope with global warming problem in Korea and to develop industry and policy related to greenhouse gas emission regulation. Currently, studies on carbon capture and storage (CO2 capture and storage) are under way.

Carbon dioxide storage technologies include ocean storage technology, geologic storage technology, and mineral carbonation technology. Marine storage is a method of injecting large-scale captured carbon dioxide into ocean deep seawater or injecting it into the ocean floor for long term isolation. This method is known to destroy marine ecosystems relatively rapidly, and since it can not guarantee long-term and stable in-ocean storage of deep-sea water or carbon dioxide injected into the ocean floor, It is true.

And underground storage is a technology that injects large-scale captured carbon dioxide into a stable geological structure existing at 800m ~ 1000m depths on the land or sea floor and isolates it in the long term and is actively studied in connection with oil and natural gas development projects in various advanced countries. Among the three carbon dioxide storage technologies, it is considered to be the most technologically and economically most effective. Accordingly, this technology has been filed in various patents on a process for storing carbon dioxide captured in a marine sediment layer for a long period of time in a supercritical state as in Patent Documents 1 and 2. However, Such as ecosystem threats, depletion of aquifers and depletion of groundwater resources, contamination of soil and groundwater due to increased fluidity of heavy metals and other contaminants, ground bumps, earthquake induction, and gas hydrate irritation.

Mineral carbonation technology is a technology for chemically reacting carbon dioxide with metal oxide such as calcium and magnesium to store carbon dioxide in an insoluble carbonate mineral state. It is a technique of direct carbonation and indirect carbonation, Technology. Direct carbonation is a single process in which carbon dioxide reacts directly with the raw material and is carbonated. Indirect carbonation is the carbonation of intermediate substances by extracting (eluting) a highly reactive Ca / Mg compound from the raw material.

Raw materials for mineral carbonation can be largely divided into natural minerals and industrial byproducts. Because Korea has a small amount of natural minerals, mineral carbonation using them is difficult. On the other hand, industrial by-products such as waste concrete / cement, steel slag generated in steelmaking processes, and ash, which is a by-product of combustion, are continuously generated every year and can be supplied stably. As a technology related to mineral carbonation using industrial by-products, Patent Document 3 discloses a method of storing carbon dioxide, which includes a step of bringing a slurry mixture containing pulverized dolomite fine powder into contact with carbon dioxide, and Patent Document 4 discloses a method of storing carbon dioxide A method of storing carbon dioxide using a fly ash and an organic wastewater enhancer for capturing carbon dioxide by reacting a mixture of leachate and an organic wastewater enhancer with carbon dioxide, and Patent Document 5 discloses a method of storing carbon dioxide by slag and electric furnace generated in a process such as a blast furnace, There are various methods of storing carbon dioxide using byproducts such as a method in which carbon dioxide is immobilized using a converter slag generated in a furnace.

In the present invention, a cement kiln dust (CKD) generated as a by-product in the cement industry was used. CKD is a fine particle collected by a dust collector in the cement manufacturing process, the scattered dust in the limestone raw material crushing process and the gas generated by heating the crushing raw material to a relatively low temperature of about 550 at the upper part of the preheater before being put into the kiln. CKD production is estimated to be about 5 million tonnes based on domestic cement production of 50 million tonnes in 2009, which is roughly 7 ~ 15% of cement production.

In the past, CKD was the main cause of environmental pollution, which is released into the atmosphere. Currently, dust collector is installed and most of it is collected and reused in kiln. However, the recycled CKD is a fine particle that repeatedly circulates the production process of cement such as preheater, thereby reducing the production efficiency of the cement and forming a coating film inside the kiln and the preheater, (Refer to non-patent document 2).

Patent Document 1: Japanese Patent Application Laid-Open No. 20-238054 (published on October 10, 2008) Underground storage system of carbon dioxide Patent Document 2: Korean Published Patent Application No. 2010-0068089 (published on June 22, 2010) Detailed Process for Carbon Dioxide Underground Storage Patent Document 3: Korean Patent Laid-Open Publication No. 2011-0076689 (published on 07. 08, 2011) Carbon dioxide storage method and carbon dioxide storage device Patent Document 4: Korean Registered Patent No. 1128492 (registered on Mar. 13, 2012) Storage method of carbon dioxide using fly ash and organic waste water enhancer Patent Document 5: Korean Patent Registration No. 0891551 (registered on Mar. 26, 2009) Carbon dioxide immobilization method by mineral carbonation of steel industry slag

Non-Patent Document 1: Cho, YJ. (2008) Analysis of GHG emissions by industry using industry association analysis. SUSTAINABILITY ISSUE PAPERS 94, 1-10. Non-Patent Document 2: Development of a solidifying agent for floor construction of a sports facility using dusted cement and CKD during cement manufacturing process. Chungju National University Industrial Science Research 27, 1-8. Non-Patent Document 3: Erin R. Bobicki, Qingxia Liu, Zhenghe Xu *, Hongbo Zeng (2012) 'Carbon capture and storage using alkaline industrial wastes Progress in Energy and Combustion Science 38, 302-320

The present invention relates to a cement kiln dust (CKD) which is produced as a by-product in a cement industry by dissolving Ca in a solvent and reacting the Ca effluent with carbon dioxide to convert it into a stable mineral calcium carbonate (CaCO ₃ ) And the carbon dioxide storage effect is enhanced by indirectly carbonating the cement kiln dust. The present invention also provides a method for storing carbon dioxide by indirect carbonating the cement kiln dust.

So far, industrial by-products used as mineral carbonating materials have a large particle size, requiring pretreatment such as crushing and crushing, and the problem of pre-treatment cost and energy consumption is high. In particular, CKD, which is a by-product of the cement industry used in the present invention, has a CaO content of not less than 40% by weight, facilitates carbonation reaction, and can be continuously produced and stably maintained every year. It is suitable as raw material of mineral carbonation because it does not go through the pretreatment step of crushing and it is possible to recycle industrial byproducts with less energy consumption and environmentally friendly.

The present invention relates to a method for producing Ca, comprising the steps of: adding a cement kiln dust to a solvent and stirring to produce an eluate containing Ca;

Separating the sediment from the eluate; And

Reacting the effluent from which sediment is separated with carbon dioxide to produce calcium carbonate;

The present invention provides a method for indirect carbonating a cement kiln dust to store carbon dioxide.

The present invention is advantageous in that CKD for storing carbon dioxide can be stably secured as a by-product generated in the cement industry and can be used as a raw material for mineral carbonation with high carbonation efficiency. And the solvent which can dissolve the Ca component as much as possible is selected and the efficiency and efficiency are increased by selecting the appropriate concentration and liquid ratio. Also, since the high purity calcium carbonate produced according to the present invention is widely used in various industrial fields, it is expected to have high economic value by recycling and additionally economical efficiency in the implementation of carbon emission trading system.

1 is an indirect carbonation process diagram for eluting Ca and using a solvent of the present invention to react with carbon dioxide to produce calcium carbonate
FIG. 2 is a graph showing the Ca elution efficiency according to the concentration of a solvent (ammonium chloride, ammonium acetate, acetic acid, hydrochloric acid) according to Examples and Comparative Examples of the present invention
FIG. 3 is a graph showing the Ca dissolution efficiency according to the ratio of the solvent (ammonium chloride, ammonium acetate, acetic acid, hydrochloric acid) and CKD according to the examples and comparative examples of the present invention
4 is a graph showing the X-ray diffraction (XRD, PHILIPS (Netheland)) peaks of the salts produced using the solvents of Examples 1 and 2, respectively, according to the present invention.
(a) CaCO ₃ (b) Use ammonium chloride solvent (c) Use ammonium acetate solvent

A method of indirectly carbonating a cement kiln dust according to the present invention for storing carbon dioxide to achieve the above effects will now be described with reference to FIGS. 1 to 4 attached hereto for understanding the technical structure of the present invention. It should be noted that the description of the other portions will be omitted so as not to obscure the gist of the present invention.

As shown in FIG. 1, in the method of indirectly carbonating a cement kiln dust according to the present invention and storing carbon dioxide,

Adding a cement kiln dust to the solvent and stirring to prepare an eluate containing Ca;

Separating the sediment from the eluate; And

Reacting the effluent from which sediment is separated with carbon dioxide to produce calcium carbonate;

.

The raw material for industrial waste used in the present invention is a cement kiln dust (CKD) generated as a by-product in the cement industry. When CKD is analyzed by using X-ray Fluorescence Spectrometer [XRF, SHIMADZU (Japan)], CKD is composed of CaO, SiO _{2 ,} Al ₂ O _{3 ,} K ₂ O and MgO as shown in Table 1 below , And the content of CaO was 42.66%, indicating that industrial waste having a high content of Ca, which is a main component of carbonation reaction.

In addition, the particle size of CKD affects Ca elution. As a result of laser diffraction particle size analysis, it was found that CKD was very fine particles having a size of 23.08 μm. Compared to other fine industrial byproducts, CKD is much smaller in particle size. Considering the typical size of the particles, the particle size of CKD is smaller than the particle size of other industrial wastes, considering that the fly ash is 40 μm and the oil shale as is 100 μm in size can do. Therefore, CKD can be used as a raw material for carbonation without pretreatment steps of crushing and crushing, and it has been proved that the energy required for the pretreatment is saved, which is a highly economical industrial byproduct.

The solvent used in the Ca eluant preparation step is ammonium chloride or ammonium acetate.

The concentration of the solvent is preferably 0.70 to 1.74M. When the concentration of the solvent is less than 0.70M, Ca may not sufficiently elute from the CKD. If the concentration of the solvent exceeds 1.74M, the amount of Ca eluted from the CKD does not increase with the concentration of the solvent. .

CKD is preferably added in an amount of 2 to 10 g per 100 mL of solvent so that sufficient Ca can be eluted. When the addition amount of CKD is less than 2 g, there is a possibility that the elution concentration of Ca in the eluent is lowered. When the addition amount of CKD is more than 10 g, Ca contained in CKD may not be eluted sufficiently.

It is also preferable that the elution condition of Ca from CKD is stirred at a temperature of 25 to 40 DEG C at a stirring rate of 100 to 300 rpm for 10 minutes to 2 hours. When the elution condition is less than the above defined range, Ca contained in the CKD may not be sufficiently eluted. When the elution condition exceeds the range defined above, the Ca elution amount increases in proportion to the exceeding range There is an uneconomical problem.

On the other hand, in the step of separating the sediment from the eluate, the reaction suspension is filtered with a 0.45 mu m membrane filter to separate the eluate from the sediment.

In the step of producing calcium carbonate, the carbonation reaction using the eluent and carbon dioxide is preferably carried out at a temperature of 25 to 80 ° C for 30 minutes. If the amount is less than the above-defined range under the carbonation reaction conditions, the carbonation reaction does not sufficiently proceed, and the yield of the calcium carbonate may be lowered. When the amount exceeds the above-defined range, There is an uneconomical problem because the production yield of calcium is not increased.

Hereinafter, embodiments according to the present invention will be described in detail below, but the technical composition of the present invention is not necessarily limited to the following embodiments.

1. Securing and analyzing sample material (CKD)

The CKD used in this example was supplied by D cement company, homogenized by mixing well, and stored in a desiccator. The components of CKD were analyzed by XRF (X-ray Fluorescence Spectrometer) and the results were as shown in Table 1 below. As a result, CaO, SiO _{2 ,} Al ₂ O _{3 ,} K ₂ O, MgO , And the content of CaO was the highest at 42.66 wt%. It was confirmed that CKD, which is a main component of carbonation reaction and high in Ca content, is a suitable material for mineral carbonated material.

ingredient CaO SiO ₂ Al ₂ O ₃ K ₂ O MgO Fe ₂ O ₃ SO ₃ Content (% by weight) 42.66 13.67 4.56 3.44 2.78 2.09 0.94

In order to measure the exact particle size of CKD, particle size analysis using a Laser Scattering Particle Size Analyzer [Sympatec GmbH (Germany)] showed that the particle size was 23.08 μm.

2. Preparation of Ca eluate

(Example 1)

50 mL of an ammonium chloride solution having a concentration of 1.74 M was placed in an Erlenmeyer flask and pH was measured. Then, 5 g of CKD was added to fix the liquid ratio (solid g: liquid mL) at 1:10. The Erlenmeyer flask was placed in a thermostatic stirrer and stirred at 25 DEG C and 200 rpm for 30 minutes. The reaction suspension was filtered through a 0.45 mu m membrane filter to prepare an eluate.

(Example 2)

50 mL of an ammonium acetate solution having a concentration of 1.74 M was placed in an Erlenmeyer flask, and after pH measurement, 5 g of CKD was added to fix the liquid ratio (solid g: liquid mL) at 1:10. The experiment was carried out in the same manner as in Example 1 to prepare an eluate.

(Example 3)

50 mL of an ammonium chloride solution having a concentration of 0.70 M was placed in an Erlenmeyer flask, and 5 g of CKD was added to the flask to fix the solid ratio (solid g: liquid mL) to 1:10. The experiment was carried out in the same manner as in Example 1 to prepare an eluate.

(Example 4)

50 mL of an ammonium acetate solution having a concentration of 0.70 M was placed in an Erlenmeyer flask, and after pH measurement, 5 g of CKD was added to fix the liquid ratio (solid g: liquid mL) at 1:10. The experiment was carried out in the same manner as in Example 1 to prepare an eluate.

(Example 5)

50 mL of an ammonium chloride solution having a concentration of 1.74 M was placed in an Erlenmeyer flask, and 1 g of CKD was added thereto to fix the solid ratio (solid g: liquid mL) to 1:50. The experiment was carried out in the same manner as in Example 1 to prepare an eluate.

(Example 6)

50 mL of an ammonium acetate solution having a concentration of 1.74 M was placed in an Erlenmeyer flask and 1 g of CKD was added thereto to fix the liquid ratio (solid g: liquid mL) at 1:50. The experiment was carried out in the same manner as in Example 1 to prepare an eluate.

(Comparative Example 1)

50 mL of acetic acid solution having a concentration of 1.74 M was placed in an Erlenmeyer flask and the eluate was prepared by conducting the same experiment as in Example 1.

(Comparative Example 2)

50 mL of a hydrochloric acid solution having a concentration of 1.74 M was placed in an Erlenmeyer flask, and the eluate was prepared by conducting the same experiment in the same liquid ratio as in Example 1.

3. Carbonation reaction

end. Reactor

The reaction tank used in this experiment was a stainless steel cylindrical reactor, and an impeller was installed inside the impeller for efficient stirring of Ca eluent and carbon dioxide, and carbon dioxide was introduced into the shaft portion of the impeller and the stirring speed was controlled. A temperature sensor and a pressure gauge were installed to measure the temperature and pressure inside the reactor, and each measured value was quantified and measured through the instrument panel. In addition, an inlet valve and an outlet valve were installed for discharging the remaining carbon dioxide after the inflow of carbon dioxide and the reaction, and a mass flow meter was installed in front of each valve to measure the amount of carbon dioxide introduced and discharged. The total volume of the reaction tank is 2L and designed to withstand high temperature (100 ℃) and high pressure (20bar).

I. Carbonation reaction

An elution solution eluted by the methods of Examples 1 to 6 and Comparative Examples 1 and 2 was prepared. Each of the Ca eluate (500 mL) was placed in the reaction tank and completely closed. The outflow valve was closed and the inlet valve was opened to inject carbon dioxide. Carbon dioxide was sufficiently injected until the internal pressure of the reaction vessel reached 5 bar, the inlet valve was closed, and the stirring speed was adjusted to 300 rpm to react at 25 to 80 ° C. for 30 minutes. The pressure drop during the reaction was measured according to the change of time. After 30 minutes, the remaining carbon dioxide in the reaction tank was discharged without opening the outlet valve.

All. Carbonate recovery

After the carbonation was completed in the reaction vessel, the sealed reaction vessel was opened and closed to transfer the solution to the beaker. When the carbonate was formed, the solution was allowed to stand at room temperature until the salt subsided, and the supernatant was separated. The recovered salt was washed with ultrapure water and then dried in a freeze-drier. The components were identified by XRD analysis and the purity was measured based on CaCO ₃ . 4). As a result of analyzing the components of the salt produced using XRD, FIG. 4 shows the results of analysis of ammonium chloride (FIG. 4 b) of Example 1 and ammonium acetate (FIG. The peak of the salt produced using each of the solvents was the same as the calcium carbonate (CaCO ₃ ) peak (FIG. 4 a). The resulting salt was weighed and the CO ₂ stock was calculated [Table 2].

division Ca elution condition Ca elution
efficiency
(%) Carbonation temperature
(° C) Carbonic acid
calcium
(g) Carbonation rate (%) carbon dioxide
Amount of storage
(kg CO ₂ / ton CKD) menstruum density
(M) High liquid fee Example One Ammonium chloride 1.74 1:10 86.9 25 41.6 89.2 318 2 Ammonium acetate 1.74 1:10 85.4 80 39.7 81.2 297 3 Ammonium chloride 0.70 1:10 36.2 25 19.3 100 61 4 Ammonium acetate 0.70 1:10 36.6 80 19.5 99.7 63 5 Ammonium chloride 1.74 1:50 87.5 25 8.5 91.5 327 6 Ammonium acetate 1.74 1:50 84.3 80 7.5 80.9 278 Comparative Example One Acetic acid 1.74 1:10 93.7 80 14.8 14.8 61 2 Hydrochloric acid 1.74 1:10 94.3 80 0 0 0

In Example 5, a large amount of carbon dioxide such as 327 kg CO ₂ / ton CKD was stored by carbonation, whereas in the case of using slag in Table 3, 90 kg CO ₂ / ton slag, 160 kg CO ₂ / ton As shown by slag, the present invention shows that the carbon dioxide storage efficiency is 2 to 3.6 times higher than in the prior art.

Raw material Solvent used Carbon dioxide storage CKD ^a Ammonium chloride 327 kg CO ₂ / ton CKD Slag ^b Acetic acid 90 kg CO ₂ / ton slag Slag ^c Ammonium chloride 160 kg CO ₂ / ton slag

b : 비특허문헌 3의 [표 3]에 '0.09kg CO₂/kg slag'가 기재되어 있음
c : 비특허문헌 3의 [표 3]에 '0.16kg CO₂/kg slag'가 기재되어 있음a: Example 5 < basis for calculation of carbon dioxide storage amount >
Carbonation reaction: CaO + CO ₂ → CaCO ₃

b: 0.09 kg CO ₂ / kg slag is listed in [Table 3] of the non-patent document 3
c: "0.16 kg CO ₂ / kg slag" is listed in [Table 3] of the non-patent document 3

2, which is a drawing attached to the present invention, is a graph showing Ca dissolution efficiency according to the concentration of a solvent (ammonium chloride, ammonium acetate, acetic acid, hydrochloric acid) according to Examples and Comparative Examples of the present invention. FIG. 4 is a graph showing the Ca elution efficiency according to the ratio of a solvent (ammonium chloride, ammonium acetate, acetic acid, hydrochloric acid) and CKD according to the examples and comparative examples of the present invention. example 2 a salt of X-ray Diffraction (XRD, PHILIPS (Netheland)) generated using respectively, the solvent peak as shown in the graph, (a) is CaCO ₃ (B) is the ammonium chloride solvent use graph, and (c) is the ammonium acetate solvent use graph.

As described above, the method of indirectly carbonating the cement kiln dust according to the present invention to store carbon dioxide has been described with reference to the preferred embodiments. However, those skilled in the art will recognize that the following It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (5)

Adding 2 to 10 g of cement kiln dust to 100 ml of a solvent having a concentration of 1.74 M and stirring at a temperature of 25 to 40 캜 at a stirring speed of 100 to 300 rpm for 10 minutes to 2 hours to prepare an Ca-
Separating the sediment from the eluate; And
Reacting the effluent from which sediment is separated with carbon dioxide at 25 to 80 ° C for 30 minutes to produce calcium carbonate;
Lt; / RTI &gt;
Wherein the solvent is ammonium chloride or ammonium acetate, and the carbon dioxide is treated by indirect carbonation. delete delete delete delete

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