Apparatus for continuous mineral carbonation based on direct carbonation and method for continuous mineral carbonation using same

Abstract

The present invention relates to an apparatus for continuous mineral carbonation based on direct carbonation and a method for continuous mineral carbonation using same and, more specifically, to an apparatus for continuous mineral carbonation and a method for continuous mineral carbonation using same, wherein the apparatus comprises: an absorption tower that absorbs CO2 from a CO2-containing exhaust gas by means of an alkaline absorbent solution, discharges purified exhaust gas, and discharges a CO2-containing absorbent solution; a slag feeding device that feeds industrial by-products containing calcium oxide (CaO) into a carbonization reactor; the carbonation reactor in which a carbonation reaction occurs between the CO2-containing absorbent solution discharged from the absorption tower and the industrial by-products containing calcium oxide (CaO); and a conveying unit that continuously conveys, to a storage unit, a mixture discharged from the carbonization reactor.

Description

Continuous mineral carbonation device using direct carbonation and mineral carbonation method using the same

[0001] The present invention relates to a continuous mineral carbonation device and a mineral carbonation method using the same, and more particularly, to a continuous mineral carbonation device of a direct carbonation method that improves the solubility of CO2 using an alkaline aqueous solution and improves energy efficiency by not involving a dissolution process, and to a mineral carbonation method using the same.

[0002] Mineral carbonation technology is a useful means of permanently storing CO2 by reacting alkaline earth metal components contained in minerals with CO2 to produce thermodynamically safer carbonate minerals.

[0003] Mineral carbonation can be divided into indirect carbonation, which extracts alkaline cations and reacts them with CO2, and direct carbonation, which directly reacts alkaline industrial byproducts with CO2. More specifically, the difference between these two technologies is that indirect carbonation aims to extract effective ingredients by adding a base or acid solution to slag, which is then reacted with CO2 to produce high-purity CaCO3 and utilize it, whereas direct carbonation aims to directly react CO2 with slag, fixing it, and processing it. While both result in the production of CaCO3 or MgCO3, indirect carbonation inevitably goes through a dissolution process to achieve high purity, and this process is energy-inefficient, making it clearly distinct from direct carbonation, which does not have a dissolution process, in terms of CO2 processing.

[0004] The direct carbonation method can reduce the cost of CO2 treatment because it can react with CO2 without a separate cation extraction process. For example, Korean Patent Application No. 10-2020-7008198 relates to a continuous manufacturing method of solidified steelmaking slag and a related device. It is a technology that cools high-temperature slag and captures and processes CO2. Although it is based on the direct carbonation reaction, it corresponds to a gas-solid carbonation method that sprays CO2 in a gaseous state onto the high-temperature slag. However, this type of reaction has the problem of significantly low reaction efficiency. For example, at approximately 600℃, even after reaction for more than an hour, the CO2 capture capacity is only about 88.5 g-CO2 / kg-slag. When the temperature is lowered to room temperature, even after reaction for 6 hours, the CO2 capture capacity is only about 11.4 g-CO2 / kg-slag. In addition, the gas-solid carbonation method has the problem that it must go through a process of natural carbonation again by being stored in the open air because there is free CaO that can additionally absorb CO2.

[0005] Therefore, a gas / liquid reaction in an aqueous solution can be an alternative. Meanwhile, since the CO2 absorption amount in the gas / liquid direct carbonation method varies depending on temperature, pressure, reaction rate, and particle size of the reactants, various types of reactors have been proposed to control these factors. Reactors such as autoclave reactors, batch reactors, and slurry reactors have been widely used to control the temperature and pressure of mineral carbonation to absorb CO2. However, continuous operation is difficult due to the essential process of separating solids and liquids and drying after the CO2 reaction. Recently, reactors such as the rotating packed bed (RPB) reactor and ultrasonic reactor have been proposed to improve the mass transfer rate, but these have the problem of difficult process scale-up. Therefore, there is a need for improvement to a process that can continuously react with CO2 and be scaled up.

[0006] [Prior Art Literature]

[0007] [Patent Document]

[0008] Korean Patent Application No. 10-2020-7008198

[0009] One aspect of the present invention is to provide a continuous mineral carbonation device of a direct carbonation method that improves the solubility of CO2 using a basic aqueous solution and improves energy efficiency by not involving a dissolution process.

[0010] Another aspect of the present invention is to provide a continuous mineral carbonation method that can secure high CO2 capture efficiency by using a continuous mineral carbonation device of the direct carbonation method as described above and that can be scaled up to a large-scale process.

[0011] According to one aspect of the present invention, a continuous mineral carbonation device is provided, comprising: an absorption tower for absorbing CO2 in flue gas containing CO2 with an alkaline absorbent, discharging purified flue gas, and discharging the CO2-containing absorbent; a slag injection device for injecting an industrial by-product containing calcium oxide (CaO) into a carbonation reactor; a carbonation reactor for carbonating the CO2-containing absorbent discharged from the absorption tower and the industrial by-product containing calcium oxide (CaO); and a transfer unit for continuously transferring a mixture discharged from the carbonation reactor to a storage unit.

[0012] According to another aspect of the present invention, a continuous mineral carbonation method is provided, comprising: a step of absorbing CO2 in a flue gas containing CO2 with an alkaline absorbent using the continuous mineral carbonation device of the present invention, discharging purified flue gas, and preparing a CO2-containing absorbent; a step of performing a carbonation reaction by mixing the CO2-containing absorbent with an industrial by-product containing calcium oxide (CaO); and a step of continuously transporting and storing the mixture discharged as a result of the carbonation reaction.

[0013] The liquid-solid carbonation method according to the present invention can secure high CO2 capture efficiency in a short period of time based on the direct carbonation method, and this difference in CO2 capture performance appears to be even greater when actually stacked. That is, according to the present invention, the aging time in a stacking yard using a mineral carbonation reaction can be shortened to within several hours, and since the need for stacking slag for a long period of time is eliminated, the space efficiency of the slag stacking yard can be improved, and scale-up to a commercially large-scale process is possible using a screw reactor, a conveyor belt, etc.

[0014] Figure 1 schematically illustrates the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, which is provided with a slag inlet (102) and a conveying section (400) in the form of a screw (A).

[0015] Figure 2 schematically illustrates the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, which is provided with a slag input section (102) and a transport section (400) in the form of a conveyor (B).

[0016] Figure 3 shows the CO2 absorption amount of slag by particle size. Figure 3(a) shows the CO2 absorption amount in the case of 0.75 mol of NaHCO3, and Figure 3(b) shows the CO2 absorption amount in the case of 1.00 mol of NaHCO3. Figures 3(a) and 3(b) were both experiments conducted using steelmaking slag, respectively.

[0017] Figure 4 is a graph showing the change in pH (a) and CO2 absorption rate (%) (b) over time during a continuous mineral carbonation reaction process using direct carbonation using blast furnace slag.

[0018] Figure 5 is a graph showing the change in pH (a) and CO2 absorption rate (%) (b) over time during a continuous mineral carbonation reaction process using direct carbonation using KR slag.

[0019] Figure 6 is a graph showing the CO2 absorption amount (gCO2 / kg_slag) according to pH change based on the difference in particle size in a continuous mineral carbonation reaction of the direct carbonation method using KR slag.

[0020] Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0021] The present invention proposes a continuous direct carbonation device and method.

[0022] Hereinafter, the mineral carbonation device of the present invention will be described.

[0023] The continuous mineral carbonation device of the present invention comprises: an absorption tower for absorbing CO2 in a flue gas containing CO2 with an alkaline absorbent, discharging purified flue gas, and discharging a CO2-containing absorbent; a slag feeding device for feeding an industrial by-product containing calcium oxide (CaO) into a carbonation reactor; a carbonation reactor for carrying out a carbonation reaction between the CO2-containing absorbent discharged from the absorption tower and the industrial by-product containing calcium oxide (CaO); and a conveying unit for continuously conveying a mixture discharged from the carbonation reactor to a storage unit.

[0024] Referring to the continuous mineral carbonation device of the direct carbonation method of the exemplary embodiment of the present invention illustrated in FIG. 1, the present invention includes a slag feeder (100) for injecting slag, a carbonation reactor (200) for performing a carbonation reaction, an absorption unit (300) including an absorber (301) for improving the solubility of liquid CO2 to promote the carbonation reaction, and a conveying unit (400) for conveying slag on which the carbonation reaction has been completed.

[0025] Meanwhile, some sections of the transport section may be equipped with a washing section (500) in which a washing reaction using water may be performed. Such a washing section is for washing a mixture discharged from a carbonation reactor transported by the transport section, and may be a washing section using water.

[0026] A slag feeder (100) may include a hopper including a receiving space for receiving industrial by-products including calcium oxide, and a slag feeder provided at the bottom of the hopper for continuously feeding industrial by-products including calcium oxide discharged from the hopper into a carbonation reactor. For example, the slag feeder (102) may be configured in various ways, such as a screw type (A) or a conveyor type (Fig. 2, (B)), as a device for transporting slag filled in the hopper (101) to the upper part of the carbonation reactor (200). The slag feeder is used for the purpose of controlling the amount of slag injected into the upper part of the carbonation reactor.

[0027] The carbonation reactor (200) may be configured as a batch reactor, and a CO2-containing absorbent, for example, a NaHCO3 solution, may be injected from the top to the bottom of the carbonation reactor. At this time, the total reaction time can be controlled according to the liquid flow rate, and since the CO2-containing absorbent moves along the surface of the slag, a mineral carbonation reaction occurs on the surface of the slag. The carbonation reactor can be controlled to smoothly transport the powder by using a vibration pad or a striking device.

[0028] The above carbonation reactor is formed in a batch type, and after slurry is introduced into the upper part thereof to fill the reactor, a solution containing dissolved CO2 can be sprayed into the upper part of the reactor. At this time, the method of spraying is not particularly limited, and various methods such as spray type and distributor can be applied.

[0029] The absorption tower (301) of the absorption unit (300) is a section that absorbs CO2 through an acid-base reaction. An alkaline absorption liquid, for example, a NaOH solution, is injected from the upper part to the lower part by injection, for example, through an injection nozzle, and a gas containing CO2 moves from the lower part of the absorption tower to the upper part. In this process, CO2 is absorbed through a cross reaction between the liquid and the gas, and CO2-free exhaust gas is discharged.

[0030] The conveying unit (400) can improve the reaction time by reacting the slag with a CO2-containing absorbent, for example, a NaHCO3 solution, while the slag is being conveyed, thereby inducing an additional mineral carbonation reaction, and the slag in which the mineral carbonation reaction is completed can be recovered and utilized in a bucket (30) at the bottom of the conveying unit. At this time, the conveying unit (400) can be configured in a screw form (A) or a conveyor form (Fig. 2, (B)).

[0031] In the above-mentioned transfer unit (400), the liquid can be discharged downward, and the material thereof is not particularly limited, but may be in the form of a mesh such as a Teflon mesh or a stainless steel mesh, for example. The discharged liquid can be reused in the CO2 absorption unit through a pump (20). Alternatively, the discharged liquid can be collected and transferred to a separately provided H2O tank (not shown).

[0032] Meanwhile, the solid supplied to the above-described conveying unit (400) is not discharged downward, and the supplied solid can be conveyed in a certain direction. For example, it can be conveyed to a slag bucket (30). At this time, the screw thread of the conveying unit may be such that the lower part of the inlet (outlet) that discharges downward is screwed in a forward direction, but the upper part of the inlet is screwed in a reverse direction, and in this case, the solid can be prevented from moving beyond the outlet.

[0033] FIG. 1 schematically illustrates the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, in which a batch reactor (200) and a slag input section (102) and a conveying section (400) of a screw type (A) are connected and provided, and FIG. 2 illustrates a case in which a batch reactor (200) and a slag input section (102) and a conveying section (400) of a conveyor type (B) are connected and provided.

[0034] The above alkaline absorbent is not particularly limited as long as it is an alkali that can be suitably used to absorb acidic gases in exhaust gas, but may be selected from sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), etc., and specifically may be sodium hydroxide. The following description will be given using sodium hydroxide absorbent as an example among alkaline absorbents. When the above alkaline absorbent is a sodium hydroxide (NaOH) aqueous solution, the CO2-containing absorbent may be a sodium bicarbonate (NaHCO3) aqueous solution.

[0035] The above sodium hydroxide absorbent can remove carbon dioxide contained in exhaust gas through a carbonation reaction of the following formula (1).

[0036] NaOH (aq) + CO2(g) → NaHCO3(aq) (1)

[0037] According to the above equation (1), carbon dioxide can react with sodium hydroxide to form a salt in the form of sodium bicarbonate (NaHCO3).

[0038] Meanwhile, since carbon dioxide has a very low solubility in water (0.0329 mol / L@25℃), the solubility of carbon dioxide can be improved and the mineral carbonation reaction can be activated by using an alkaline absorbent such as NaOH solution.

[0039] More specifically, the rate-determining step in mineral carbonation is the rate at which CO2 dissolves in water. For example, NaOH, a basic solution, activates acid-base reactions by reacting with CO2, an acidic gas. When NaOH and CO2 react, CO2 dissolves in the liquid phase in the form of NaHCO3, as shown in Equation (1) above, increasing the amount of dissolved CO2 in the liquid phase. The dissolved CO2 spontaneously reacts with alkaline earth metals (CaO, MgO, etc.), forming minerals in the form of CaCO3 or MgCO3, which can sequester CO2.

[0040] CaO (s) + H2O (l) → Ca(OH)2(s) (2)

[0041] Ca(OH)2+ 2NaHCO3(aq) → CaCO3(s) + NaOH (aq) + H2O (aq) (3)

[0042] There is no lower limit to the concentration of the alkaline absorbent, but specifically, it may be 0.1 M to 1.0 M, and more specifically, it may be 0.5 M to 0.8 M. If the concentration of the alkaline absorbent is less than the above range, the amount of acid gas absorbed into the alkaline absorbent decreases, and thus the circulation amount of the absorbent increases in order to absorb a large amount of acid gas, which may cause the size of the mineral carbonation device to become excessively large. If the concentration exceeds the above range, the amount of carbon dioxide dissolved in sodium bicarbonate or potassium bicarbonate increases, which may precipitate in a solid form, which may cause problems such as clogging of the absorption tower.

[0043] Meanwhile, the slag feeder of the present invention may include a slag feeder (102) that continuously feeds industrial byproducts containing calcium oxide for a continuous carbonation reaction, and the shape of the slag feeder is not particularly limited, but may be in the shape of a conveyor belt or a screw.

[0044] The above-mentioned transport unit can appropriately adjust the transport speed to optimize the removal reaction of carbon dioxide or sulfur dioxide contained in industrial byproducts and absorbent liquid. For example, the transport speed can be adjusted to a speed that allows the carbonation reaction to be performed for 30 minutes to 5 hours, preferably 1 hour to 3 hours.

[0045] The above industrial byproduct containing calcium oxide is an industrial byproduct generated in the steelmaking process, and is generated in the process of removing carbon, silicon, and sulfur components dissolved in the molten iron, and contains a large amount of calcium oxide (CaO) as it is generated at a high temperature.

[0046] The industrial by-product containing the above calcium oxide is not particularly limited, but may be selected from the group consisting of at least one slag selected from the group consisting of steelmaking slag, blast furnace slag, and KR slag; coal ash; fly ash; cement kiln dust; and chlorine bypass system dust.

[0047] Meanwhile, the industrial by-product containing the calcium oxide may have a particle size of 0.075 mm or less, for example, greater than 0.001 mm, 0.6 mm or less, or 0.075 mm or less, and preferably 0.001 to 0.075 mm or less. When the industrial by-product containing the calcium oxide has a particle size of 0.075 mm or less, the CO2 absorption amount and absorption rate can be significantly improved.

[0048] When using sodium hydroxide absorbent as the above absorbent, sodium bicarbonate (NaHCO3), which is a product of the above formula (1), reacts with calcium oxide contained in the industrial byproduct at the upper part of the carbonation reactor to cause a carbonation reaction of the above formula (3), and as a result, carbon dioxide is precipitated in the form of calcium carbonate (CaCO3), which can be stably stored, and since the sodium hydroxide introduced at the beginning of the reaction is regenerated, the regenerated alkaline absorbent can be discharged to the lower part of the carbonation reactor.

[0049] Meanwhile, the waste liquid discharged after the carbonation reaction can be regenerated into an alkaline absorbent.

[0050] The continuous mineral carbonation device of the present invention can control the temperature by further including a heat exchanger to improve the acid gas removal efficiency in the absorption tower (301).

[0051] The alkaline absorbent liquid cooled in the above heat exchanger and supplied to the absorption tower may have a temperature of 5 to 50°C. If the temperature of the alkaline absorbent liquid is lower than 5°C, the salts (NaHCO3, Na2CO3) dissolved in the absorbent liquid may precipitate, causing problems such as clogging of the pipes and the filler of the absorption tower. If the temperature exceeds 50°C, the amount of carbon dioxide absorbed by the alkaline absorbent liquid may decrease, and the absorbent liquid may evaporate and be lost.

[0052] The above carbonation reactor (200) may include an absorption liquid injector, for example, an injection nozzle (303), that injects an acidic gas-containing absorption liquid. The absorption liquid injector is connected to the acidic gas-containing absorption liquid discharge port of the absorption tower and serves to inject the acidic gas-containing absorption liquid discharged from the absorption tower, thereby inducing a carbonation reaction, etc. by injecting the acidic gas-containing absorption liquid onto the upper portion of the industrial byproduct containing calcium oxide supplied in advance from the upper portion of the carbonation reactor.

[0053] It is preferable that the above acidic gas-containing absorbent be injected after the industrial by-product containing calcium oxide is supplied to the carbonation reactor.

[0054] It is desirable that the acid gas-containing absorbent supplied as the above industrial by-product be supplied at an optimal temperature for carbonation reaction, and for this purpose, a heat exchanger (not shown) may be further included.

[0055] Additionally, a pH or conductivity controller (not shown) may be further included to control the pH and sodium hydroxide concentration of the acidic gas-containing absorbent.

[0056] It is preferable that the above absorbent sprayer be configured to control the minimum amount of acid gas-containing absorbent required for carbonation reaction, etc., depending on the amount of industrial by-product input, and for this purpose, a control valve (not shown) or the like may be additionally provided.

[0057] The above process water is a liquid that can wash away the alkaline absorbent remaining in industrial by-products, and may be water (H2O), but is not particularly limited thereto. The process water used to wash industrial by-products can be discharged and circulated for the CO2 capture process. More specifically, since the gas contains moisture and evaporates during CO2 capture, the total amount of water decreases, and thus, the wash water can be used to perform the role of washing and replenishing the total amount of water.

[0058] According to another aspect of the present invention, a continuous mineral carbonation method using the continuous mineral carbonation device of the present invention is provided, and the continuous mineral carbonation method of the present invention comprises the steps of: absorbing CO2 in a flue gas containing CO2 with an alkaline absorbent, discharging purified flue gas, and preparing a CO2-containing absorbent; mixing the CO2-containing absorbent with an industrial by-product containing calcium oxide (CaO) to perform a carbonation reaction; and continuously transporting and storing the mixture discharged as a result of the carbonation reaction.

[0059] The contents described in the continuous mineral carbonation device of the present invention described above are equally applicable to the continuous mineral carbonation method of the present invention.

[0060] Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely illustrative examples to aid understanding of the present invention and are not intended to limit the scope of the present invention.

[0061] Example

[0062] 1. Manufacturing of a continuous mineral carbonation device using direct carbonation

[0063] A continuous mineral carbonation device of an exemplary direct carbonation method of the present invention was manufactured as illustrated in FIG. 1. Specifically, it comprises a slag feeder (100) for injecting slag, a carbonation reactor (200) for performing a carbonation reaction, an absorption unit (300) including an absorber (301) for improving the solubility of liquid CO2 to promote the carbonation reaction, and a conveying unit (400) for conveying slag on which the carbonation reaction has been completed. A portion of the conveying unit may be provided with a washing unit (500) in which a washing reaction using water can be performed.

[0064] The slag feeder (100) is a device that transports slag filled in a hopper (101) to the upper part of a carbonation reactor (200), and can be configured in various ways, such as a slag feeder (102) in the form of a screw (A) or a conveyor (Fig. 2, (B)). The slag feeder is used for the purpose of controlling the amount of slag injected into the upper part of the carbonation reactor.

[0065] The carbonation reactor (200) is configured as a batch reactor, and NaHCO3 solution is injected from top to bottom at the top of the carbonation reactor. At this time, the total reaction time can be controlled according to the liquid flow rate, and since NaHCO3 moves along the surface of the slag, a mineral carbonation reaction occurs on the surface of the slag. The carbonation reactor can be controlled to smoothly transport the powder using a vibration pad or a striking device.

[0066] The absorption tower (301) of the absorption unit (300) is a section that absorbs CO2 through an acid-base reaction. NaOH solution is injected from the upper part to the lower part by, for example, spraying using a spray nozzle, and gas including CO2 moves from the lower part of the absorption tower to the upper part. In this process, CO2 is absorbed through a cross reaction between liquid and gas, and CO2-free exhaust gas is discharged.

[0067] The conveying unit (400) can improve the reaction time by allowing an additional mineral carbonation reaction to occur by reacting with the NaHCO3 solution while the slag is being conveyed, and the slag in which the mineral carbonation reaction is completed can be recovered and utilized in the bucket (30) at the bottom of the conveying unit. At this time, the conveying unit (400) can be configured in a screw form (A) or a conveyor form (Fig. 2, (B)).

[0068] FIG. 1 schematically illustrates the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, in which a batch reactor (200) and a slag input section (102) and a conveying section (400) of a screw type (A) are connected and provided, and FIG. 2 illustrates a case in which a batch reactor (200) and a slag input section (102) and a conveying section (400) of a conveyor type (B) are connected and provided.

[0069] 2. Continuous mineral carbonation process using direct carbonation

[0070] As a simulation experiment for the continuous mineral carbonation reaction of the direct carbonation method of the present invention, 50 g of steelmaking slag was injected into a 500 ml Erlenmeyer flask with a 1 M NaHCO3 solution (CO2 loading 100%) or a mixed solution of 0.75 M NaHCO3 and 0.25 M NaOH (CO2 loading 75%), and the amount of CO2 absorbed over time was measured.

[0071] As the reaction progresses, the alkaline earth metals within the slag are solidified and the total inorganic carbon (TIC) in the liquid phase decreases. Therefore, the amount of CO2 absorbed by the slag can be calculated as the amount of TIC reduced compared to the initial TIC. Over time, the reaction between the slag and CO2 gradually slows down, and the endpoint at which no further reaction occurs is judged to be the maximum amount of CO2 that the slag can absorb.

[0072] As can be seen in Fig. 3, the mineral carbonation reaction time of the slag can be changed depending on the particle size / NaHCO3 concentration, and in particular, it was confirmed that slag with a particle size of 0.075 mm or less can achieve a mineral carbonation conversion of 85% or more by controlling the reaction speed of the steelmaking slag to 3 hours. Therefore, if the continuous direct mineral carbonation device according to the present invention is applied, it is expected that the reaction residence time can be secured up to about 3 hours to effectively react the slag with CO2. In addition, since the continuous mineral carbonation reaction is in co-current contact in the carbonation reactor, the residence time can be controlled by adjusting the speed of the solid and liquid, and thus the mineral carbonation reaction can be activated by increasing the contact time.

[0073] Slag type CO2 loading (%) Particle size (mm) Maximum absorption (gCO2 / kg_slag) Conversion rate (%) After 3 hours of reaction After 1 day of reaction Steelmaking slag 75 < 0.075 8 1.69 5.48 5.5 0.075~0.62 5.33 4.57 3.3 0.6~2.5 8.3 15.35 4.22.5~58.1 16.44 9.41 00 < 0.075 70.17 8.28 9.6 0.075~0.62 0.13 2.06 2.8 0.6~2.5 6.41 0.66 0.42.5~56.5 14.24 5.8

[0074] In Table 1 above, the CO2 conversion rate and CO2 absorption amount were calculated in the following manner.

[0075] 1) CO2 conversion rate

[0076] The CO2 conversion rate was measured using Analytik jena's multi NC / 3100 analyzer, and the three values ​​with a reproducibility of less than 1% were selected by measuring three times using the analyzer.

[0077] 2) CO2 absorption

[0078] The CO2 absorption amount was calculated based on the following equation (4).

[0079] Equation (4)

[0080]

[0081] 3. Confirmation of pH change and CO2 absorption rate (%) over time during the continuous mineral carbonation reaction process using the direct carbonation method.

[0082] (1) Continuous mineral carbonation using direct carbonation method using blast furnace slag

[0083] 50 g of slag was injected into an aqueous solution of NaHCO30.75 mol (H2O base), and the pH change and CO2 absorption rate (%) over time were measured. At this time, the CO2 absorption rate (%) was calculated by the following equation (5).

[0084] Equation (5)

[0085]

[0086] As a result, it was confirmed that the pH in the liquid increased as shown in Fig. 4(a) because OH- was generated as the reaction proceeded according to the following reaction equations (1) and (2).

[0087] NaHCO3→ Na + + HCO3 - Reaction formula (1)

[0088] CaO + HCO3 - → CaCO3+ OH - Reaction formula (2)

[0089] Furthermore, as can be seen in Figure 4(b), as the reaction progresses, the increase in CO2 absorption capacity, i.e., absorption rate, gradually decreases, reaching a point where no further reaction occurs. Therefore, the reaction time according to the present invention is preferably performed within 5 hours, for example, within 3 hours or within 2 hours.

[0090] (2) Continuous mineral carbonation using direct carbonation method using KR slag

[0091] By the same process as (1) above, but by changing the slag to pretreatment slag for molten iron (KR slag), the pH change and CO2 absorption rate (%) over time were measured and shown in Fig. 5, and based on the difference in particle size, the CO2 absorption amount (gCO2 / kg_slag) according to the pH change was shown as a graph in Fig. 6.

[0092] [Explanation of symbols]

[0093] 10: Flow meter 20: Pump

[0094] 30: Slag bucket 40: H2O tank

[0095] 100: Slag feeder

[0096] 101: Hopper 102: Slag inlet

[0097] 110: Gas inlet 120: Gas outlet

[0098] 200: Carbonation reactor

[0099] 300: Absorbent

[0100] 301: Absorber 302: Demister

[0101] 303: Injection nozzle 304: Line mixer

[0102] 305: Mass Flow Meter (MFC)

[0103] 400: Transport section

[0104] 500: Tax Department

[0105] (A): Screw type

[0106] (B): Conveyor type

Claims

1. An absorption tower that absorbs CO2 in flue gas containing CO2 using an alkaline absorbent, discharges purified flue gas, and discharges an absorbent containing CO2; A slag feeding device that feeds industrial by-products containing calcium oxide (CaO) into a carbonation reactor; A carbonation reactor in which a carbonation reaction of an absorption liquid containing CO2 discharged from the absorption tower and an industrial by-product containing calcium oxide (CaO) occurs; and A continuous mineral carbonation device, comprising a conveying unit for continuously conveying a mixture discharged from a carbonation reactor to a storage unit.

2. A continuous mineral carbonation device in the first paragraph, wherein the alkaline absorbent is at least one selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), and potassium carbonate (K2CO3).

3. A continuous mineral carbonation device in the first paragraph, wherein the alkaline absorbent is a sodium hydroxide (NaOH) aqueous solution, and the CO2-containing absorbent is a sodium bicarbonate (NaHCO3) aqueous solution.

4. A continuous mineral carbonation device according to claim 1, wherein the industrial by-product containing calcium oxide is at least one slag selected from the group consisting of steelmaking slag, blast furnace slag, and pretreatment slag for hot metal; at least one slag selected from the group consisting of coal ash; fly ash; cement kiln dust; and chlorine bypass system dust.

5. A continuous mineral carbonation device in the first paragraph, wherein the industrial by-product containing calcium oxide has a particle size of more than 0.001 mm and less than or equal to 0.6 mm, or less than or equal to 0.075 mm.

6. In the first paragraph, the slag injection device comprises a hopper including a receiving space for receiving an industrial by-product including calcium oxide, and A continuous mineral carbonation device, comprising a slag inlet provided at the bottom of the above hopper and continuously injecting industrial by-products containing calcium oxide discharged from the hopper into a carbonation reactor.

7. In paragraph 6, the slag inlet is a continuous mineral carbonation device that continuously injects industrial by-products containing calcium oxide into a carbonation reactor by means of a screw or conveyor shape.

8. A continuous mineral carbonation device in the first paragraph, wherein the transport unit continuously transports a mixture discharged from a carbonation reactor to a storage unit by means of a screw or conveyor shape.

9. A continuous mineral carbonation device, further comprising a washing unit for washing a mixture discharged from a carbonation reactor transported by a transport unit in the first paragraph.

10. Using a continuous mineral carbonation device according to any one of the provisions of paragraphs 1 to 9, A step of absorbing CO2 in flue gas containing CO2 with an alkaline absorbent, discharging purified flue gas, and preparing a CO2-containing absorbent; A step of performing a carbonation reaction by mixing the CO2-containing absorbent and an industrial by-product containing calcium oxide (CaO); and A continuous mineral carbonation method, comprising a step of continuously transporting and storing a mixture discharged as a result of a carbonation reaction.

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