Continuous mineral carbonation apparatus by direct carbonation and method of mineral carbonation using the same

Abstract

The present invention relates to a continuous mineral carbonation apparatus of a direct carbonation method and a mineral carbonation method using the same, and more particularly, to a continuous mineral carbonation apparatus and a continuous mineral carbonation method using the same, the continuous mineral carbonation apparatus including an absorption tower that absorbs CO2 in exhaust gas containing CO2 using an alkaline absorption solution, discharges refined exhaust gas, and discharges CO2-containing absorption solution, a slag input device that inputs an industrial by-product containing calcium oxide (CaO) into a carbonation reactor, the carbonation reactor that is a carbonation reaction of the CO2-containing absorption solution discharged from the absorption tower and the industrial by-product containing calcium oxide (CaO), and a delivery part that continuously delivers a mixture discharged from the carbonation reactor to a storage part.

Description

Technical Field

[0001] This invention relates to a continuous mineral carbonation apparatus and a mineral carbonation method using the apparatus, and more specifically, to a continuous mineral carbonation apparatus and a mineral carbonation method using the direct carbonation method, which utilizes an alkaline aqueous solution to increase the solubility of CO2, thereby improving energy efficiency because it does not involve a dissolution process. Background Technology

[0002] Mineral carbonation technology is an effective means of permanently storing CO2 by reacting the alkaline earth metal components contained in minerals with CO2 to generate thermodynamically more stable 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 lies in their approaches: indirect carbonation aims to add an alkali or acid solution to the slag to dissolve the active ingredients, which then react with CO2 to generate high-purity CaCO3 for utilization; while direct carbonation aims to directly react the slag with CO2, immobilize it, and treat it. Although both ultimately produce CaCO3 or MgCO3, indirect carbonation requires a dissolution process to achieve high purity, which reduces energy efficiency. Therefore, in terms of CO2 processing, it differs significantly from direct carbonation, which does not involve a dissolution process.

[0004] Direct carbonation eliminates the need for a separate cation extraction process to react with CO2, thus reducing the cost of CO2 treatment. For example, Korean Patent Application No. 10-2020-7008198 discloses a continuous manufacturing method and related apparatus for solidified steelmaking slag. This technology, which cools high-temperature slag and captures CO2, is based on a direct carbonation reaction, but belongs to the gas-solid carbonation method where CO2 is injected in a gaseous state onto the high-temperature slag. However, this type of reaction suffers from significantly low efficiency. For instance, at approximately 600°C, even after more than one hour of reaction, the CO2 capture capacity is only about 88.5 g-CO2 / kg-slag. When the temperature drops to room temperature, even after six hours of reaction, the CO2 capture capacity is only around 11.4 g-CO2 / kg-slag. Furthermore, the gas-solid carbonation method involves free CaO that can additionally absorb CO2, necessitating a further open-air storage and natural carbonation process.

[0005] In response, gas / liquid reactions in aqueous solutions can serve as an alternative. Furthermore, in direct gas / liquid carbonation, CO2 absorption varies depending on temperature, pressure, reaction rate, and reactant particle size; therefore, various reactor types have been proposed to control these parameters. Autoclave reactors, batch reactors, and slurry reactors are widely used to control the temperature and pressure of mineral carbonation to absorb CO2. However, continuous operation is difficult because CO2 must undergo solid-liquid separation and drying processes after the reaction. In recent years, rotating packed bed (RPB) reactors and ultrasonic reactors have been proposed to improve mass transfer rates; however, these reactors are difficult to scale up. Therefore, there is a need to improve processes that can continuously react with CO2 while achieving large-scale operation.

[0006] [Existing Technical Documents] [Patent Literature] Korean Patent Application No. 10-2020-7008198 Summary of the Invention

[0007] (a) Technical problems to be solved One aspect of the present invention is to provide a continuous mineral carbonation apparatus using a direct carbonation method, which utilizes an alkaline aqueous solution to increase the solubility of CO2, thereby improving energy efficiency because it does not involve a dissolution process.

[0008] Another aspect of the present invention is to provide a continuous mineral carbonation method that utilizes a continuous mineral carbonation apparatus with the direct carbonation method described above, thereby ensuring high CO2 capture efficiency and enabling large-scale process scaling.

[0009] (II) Technical Solution According to one aspect of the present invention, a continuous mineral carbonation apparatus is provided, comprising: an absorption tower that absorbs CO2 from waste gas containing CO2 using an alkaline absorbent, discharges purified waste gas, and discharges CO2-containing absorbent; a slag feeding device that feeds an industrial byproduct containing calcium oxide (CaO) into a carbonation reactor; a carbonation reactor for a carbonation reaction in which the CO2-containing absorbent discharged from the absorption tower reacts with the industrial byproduct containing calcium oxide (CaO); and a conveying unit that continuously conveys the mixture discharged from the carbonation reactor to a storage unit.

[0010] According to another aspect of the present invention, a continuous mineral carbonation method is provided, which utilizes the continuous mineral carbonation apparatus of the present invention, and includes the following steps: absorbing CO2 from waste gas containing CO2 using an alkaline absorbent, discharging the purified waste gas, and preparing a CO2-containing absorbent; mixing the CO2-containing absorbent with an industrial byproduct containing calcium oxide (CaO) to carry out a carbonation reaction; and continuously conveying and storing the mixture discharged as a result of the carbonation reaction.

[0011] (III) Beneficial Effects The liquid-solid carbonation method of the present invention, based on direct carbonation, can ensure high CO2 capture efficiency in a short time. This difference in CO2 capture performance will be even more pronounced in actual open-air stockpiling. That is, according to the present invention, the aging time in open-air stockpiles utilizing mineral carbonation reactions can be shortened to within a few hours, thereby eliminating the need for long-term open-air slag stockpiling. This promotes improved space efficiency in open-air slag stockpiles and allows for large-scale commercial-scale process expansion using spiral reactors and conveyor belts. Attached Figure Description

[0012] Figure 1 The schematic diagram illustrates the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, in the case of a slag feed section 102 and a conveying section 400 having a spiral configuration A.

[0013] Figure 2 The schematic diagram illustrates the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, in the case of having a slag feeding section 102 and a conveying section 400 in the form of a conveyor belt (B).

[0014] Figure 3 The CO2 absorption of slag with different particle sizes is shown. Figure 3 (a) The figure shows the CO2 absorption in the case of 0.75 mol NaHCO3. Figure 3 (b) shows the CO2 absorption in the case of 1.00 mol NaHCO3. Figure 3 (a) and Figure 3 (b) Experiments were conducted using steelmaking slag.

[0015] Figure 4 The graph illustrates the pH change (a) and CO2 absorption rate (%) over time during a continuous mineral carbonation reaction using a direct carbonation method with blast furnace slag.

[0016] Figure 5The graph shows the pH change (a) and CO2 absorption rate (%) over time during a continuous mineral carbonation reaction using KR slag direct carbonation.

[0017] Figure 6 A graph showing the CO2 uptake (gCO2 / kg_slag) as a function of pH variation in a continuous mineral carbonation reaction using direct carbonation of KR slag, based on particle size differences. Best practice

[0018] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention can be modified in many other forms, and the scope of the present invention is not limited to the embodiments described below.

[0019] This invention proposes a continuous direct carbonation apparatus and method.

[0020] The mineral carbonation apparatus of the present invention will now be described.

[0021] The continuous mineral carbonation apparatus of the present invention includes: an absorption tower that absorbs CO2 from waste gas containing CO2 using an alkaline absorbent, discharges purified waste gas, and discharges CO2-containing absorbent; a slag feeding device that feeds an industrial by-product containing calcium oxide (CaO) into a carbonation reactor; a carbonation reactor for which a carbonation reaction occurs between the CO2-containing absorbent discharged from the absorption tower and the industrial by-product containing calcium oxide (CaO); and a conveying unit that continuously conveys the mixture discharged from the carbonation reactor to a storage unit.

[0022] Reference Figure 1 The exemplary direct carbonation method of the present invention, as shown, is a continuous mineral carbonation apparatus comprising: a slag feeder 100 for injecting slag; a carbonation reactor 200 for performing a carbonation reaction; an absorption section 300 including an absorber 301 for increasing the solubility of liquid CO2 to promote the carbonation reaction; and a conveying section 400 for conveying the slag after the carbonation reaction has been completed.

[0023] In addition, a portion of the conveying section may be equipped with a cleaning section 500 that can perform a cleaning reaction using water. The cleaning section is used to clean the mixture discharged from the carbonation reactor that is conveyed through the conveying section, and the cleaning can be water-based.

[0024] The slag feeding device (slag feeder) 100 may include: a hopper having a receiving space for holding industrial by-products containing calcium oxide; and a slag feeding section disposed at the lower end of the hopper for continuously feeding the industrial by-products containing calcium oxide discharged from the hopper into a carbonation reactor. For example, as a device for conveying slag filled in the hopper 101 to the upper part of the carbonation reactor 200, it may be a spiral configuration A or a conveyor belt configuration (…). Figure 2 The slag feeding section 102 can be configured in various forms, including (B) and (C). The slag feeding device is used to control the amount of slag injected into the upper part of the carbonation reactor.

[0025] The carbonation reactor 200 can be configured as a batch reactor, and a CO2-containing absorbent, such as a NaHCO3 solution, can be added from the top to the bottom. The total reaction time can be controlled according to the liquid flow rate. The CO2-containing absorbent flows along the slag surface, thus carrying out the mineral carbonation reaction on the slag surface. The carbonation reactor can be controlled using a vibrating pad or impact device to ensure smooth powder transport.

[0026] The carbonation reactor is formed in an intermittent manner. After the slurry flows in from the top and fills the reactor, the solution containing dissolved CO2 can be sprayed towards the top of the reactor. At this time, there are no particular restrictions on the spraying method. For example, various methods such as spray type and distributor can be used.

[0027] The absorption tower 301 of the absorption section 300 is the part that absorbs CO2 through an acid-base reaction. An alkaline absorbent liquid, such as NaOH solution, is injected from the top to the bottom through a spray nozzle, for example. The gas containing CO2 moves from the bottom to the top of the absorption tower. During this process, CO2 is absorbed through the cross-reaction of liquid and gas, and CO2-free waste gas is discharged.

[0028] The conveying section 400 allows the slag to react with a CO2-containing absorbent, such as a NaHCO3 solution, during the conveying process, thus carrying out a further mineral carbonation reaction. This increases the reaction time, and the slag that has completed the mineral carbonation reaction can be recovered and reused in the hopper 30 at the lower end of the conveying section. At this time, the conveying section 400 can be in a spiral configuration (A) or a conveyor belt configuration (B). Figure 2 , B) constitutes.

[0029] In the conveying section 400, the liquid phase can be discharged downwards, and its material is not particularly limited; for example, it can be a filter screen made of polytetrafluoroethylene, stainless steel, or other similar materials. The discharged liquid phase can be reused in the CO2 absorption section using pump 20. Alternatively, the discharged liquid phase can be collected in a separately provided H2O tank (not shown).

[0030] Furthermore, the solid phase supplied to the conveying section 400 will not be discharged downwards; instead, the supplied solid phase can be conveyed in a certain direction, for example, to the slag bucket 30. In this case, the thread of the conveying section is referenced to the downward discharge inlet (outlet), with the thread on the lower side of the inlet being the positive direction and the thread on the upper side referenced to the outlet being the reverse direction. This prevents the solid phase from moving to a position above the outlet.

[0031] Figure 1 The illustration schematically shows the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, in which the batch reactor 200 is linked with the slag feeding section 102 and the conveying section 400 of the spiral configuration A. Figure 2 This refers to the case where the batch reactor 200 is linked with the slag feeding section 102 and the conveying section 400 in conveyor belt form B.

[0032] The alkaline absorbent is not particularly limited as long as it is an alkaline substance suitable for absorbing acidic gases in waste gas. It can be selected from sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), etc., specifically sodium hydroxide. The following explanation uses sodium hydroxide absorbent as an example. When the alkaline absorbent is an aqueous solution of sodium hydroxide (NaOH), the CO2-containing absorbent can be an aqueous solution of sodium bicarbonate (NaHCO3).

[0033] The sodium hydroxide absorbent can remove carbon dioxide contained in the waste gas through the carbonation reaction of the following formula (1).

[0034] NaOH(aq)+CO2(g)→NaHCO3(aq)(1) According to formula (1), carbon dioxide can react with sodium hydroxide to form a salt in the form of sodium bicarbonate (NaHCO3).

[0035] In addition, carbon dioxide has extremely low solubility in water (0.0329 mol / L at 25°C). Therefore, by using alkaline absorbents such as NaOH solution, the solubility of carbon dioxide can be increased, thereby activating the mineral carbonation reaction.

[0036] More specifically, the reaction rate in the mineral carbonation reaction is determined by the dissolution rate of CO2 in water. For example, NaOH is an alkaline solution that activates the acid-base reaction by reacting with the acidic gas CO2. When NaOH reacts with CO2, as shown in formula (1), CO2 dissolves in the liquid phase as NaHCO3, increasing the amount of dissolved CO2 in the liquid phase. The dissolved CO2 spontaneously reacts with alkaline earth metals (CaO, MgO, etc.) to generate minerals in the form of CaCO3 or MgCO3, thereby isolating CO2.

[0037] CaO(s) + H₂O(l) → Ca(OH)₂(s) (2) Ca(OH)2+2NaHCO3(aq)→CaCO3(s)+NaOH(aq)+H2O(aq)(3) The concentration of the alkaline absorbent has no lower limit, specifically it can be from 0.1M to 1.0M, and more specifically from 0.5M to 0.8M. When the concentration of the alkaline absorbent is less than the above range, as the amount of acidic gas absorbed by the alkaline absorbent decreases, the circulation volume of the absorbent will increase in order to absorb a large amount of acidic gas, which may lead to the size of the mineral carbonation device becoming too large. When the concentration of the alkaline absorbent is greater than the above range, the amount of carbon dioxide dissolved in the form of sodium bicarbonate or potassium bicarbonate increases, and it may precipitate in solid form, thus potentially causing problems such as blockage of the absorption tower.

[0038] In addition, the slag feeding device (slag feeder) of the present invention may include a slag feeding section 102 for continuously feeding industrial by-products containing calcium oxide in order to realize a continuous carbonation reaction. The shape of the slag feeding section is not particularly limited and may be in the form of a conveyor belt or a spiral.

[0039] The conveying unit can be adjusted in speed to optimize the removal of carbon dioxide or sulfur dioxide contained in industrial byproducts and absorbent liquid. For example, the conveying speed can be adjusted to allow the carbonation reaction to proceed for 30 minutes to 5 hours, preferably 1 hour to 3 hours.

[0040] The industrial byproduct containing calcium oxide is an industrial byproduct generated in the ironmaking process, which is produced in the process of removing dissolved carbon, silicon and sulfur components from molten iron. Because it is produced at high temperature, it contains a large amount of calcium oxide (CaO).

[0041] The industrial byproduct containing calcium oxide is not particularly limited and may be selected from at least one of the following: at least one slag selected from steelmaking slag, blast furnace slag and KR slag; fly ash; fly ash; cement kiln ash; and dust from chlorine bypass systems.

[0042] Furthermore, the particle size of the industrial by-product containing calcium oxide can be less than 0.075 mm, for example, it can be greater than 0.001 mm and less than 0.6 mm or less than 0.075 mm, preferably less than 0.001 mm to 0.075 mm. When the particle size of the industrial by-product containing calcium oxide is less than 0.075 mm, the CO2 absorption capacity and absorption rate can be significantly improved.

[0043] When sodium hydroxide absorbent is used as the absorbent, in the upper part of the carbonation reactor, the product of formula (1), sodium bicarbonate (NaHCO3), reacts with calcium oxide contained in the industrial byproduct to carry out the carbonation reaction of formula (3). As a result, carbon dioxide precipitates in the form of calcium carbonate (CaCO3), which can be stored stably. Furthermore, the sodium hydroxide added at the beginning of the reaction is regenerated, so the regenerated alkaline absorbent can be discharged from the lower part of the carbonation reactor.

[0044] In addition, the waste liquid discharged after the carbonation reaction can be regenerated into an alkaline absorbent.

[0045] The continuous mineral carbonation apparatus of the present invention further includes a heat exchanger to improve the removal efficiency of acidic gases in the absorption tower 301, thereby allowing for temperature regulation.

[0046] The temperature of the alkaline absorbent supplied to the absorption tower after cooling by the heat exchanger can be between 5°C and 50°C. When the temperature of the alkaline absorbent is below 5°C, the dissolved salts (NaHCO3, Na2CO3) in the absorbent will precipitate, which may cause blockage of the pipes and the packing of the absorption tower. When the temperature of the alkaline absorbent is above 50°C, the absorption capacity of the alkaline absorbent for carbon dioxide will decrease, and the absorbent may be lost due to evaporation.

[0047] The carbonation reactor 200 may include an absorbent injector, such as a nozzle 303, for injecting absorbent containing acidic gas. The absorbent injector is connected to the absorbent outlet of the absorbent containing acidic gas in the absorption tower, and functions to inject the absorbent containing acidic gas discharged from the absorption tower. Carbonation can be initiated by injecting the absorbent containing acidic gas into the upper part of the carbonation reactor, which is pre-supplied with industrial byproducts containing calcium oxide.

[0048] The absorbent containing the acidic gas is preferably injected after the industrial byproduct containing calcium oxide is supplied to the carbonation reactor.

[0049] The absorbent liquid containing acidic gas supplied to the industrial byproduct is preferably supplied at the optimal temperature for the carbonation reaction, and may also include a heat exchanger (not shown).

[0050] In addition, a pH or conductivity regulator (not shown) may be included to adjust the pH and sodium hydroxide concentration of the absorbent containing the acidic gas.

[0051] The absorbent injector is preferably equipped with a regulating valve (not shown) to adjust the minimum amount of absorbent containing acidic gases required for the carbonation reaction, etc., according to the amount of industrial by-products input.

[0052] The process water is a liquid that can clean the alkaline absorbent residue in industrial by-products; it is not particularly limited and can be water (H2O). After being discharged, the process water used to clean the industrial by-products can be recycled for the CO2 capture process. More specifically, during CO2 capture, the total water volume decreases due to the moisture in the gas evaporating; therefore, the cleaning water can be used to both clean and replenish the total water volume.

[0053] According to another aspect of the present invention, a continuous mineral carbonation method utilizing the continuous mineral carbonation apparatus of the present invention is provided. The continuous mineral carbonation method of the present invention includes the following steps: absorbing CO2 from waste gas containing CO2 using an alkaline absorbent, discharging the purified waste gas, and preparing a CO2-containing absorbent; mixing the CO2-containing absorbent with an industrial byproduct containing calcium oxide (CaO) to carry out a carbonation reaction; and continuously conveying and storing the mixture discharged as a result of the carbonation reaction.

[0054] The contents described in the continuous mineral carbonation apparatus of the present invention are also applicable to the continuous mineral carbonation method of the present invention.

[0055] The present invention will now be described in more detail through specific embodiments. These embodiments are merely examples to aid in understanding the invention, and the scope of the invention is not limited thereto. Detailed Implementation

[0056] Example Example 1. Manufacturing of a continuous mineral carbonation apparatus using direct carbonation. like Figure 1 As shown, a continuous mineral carbonation apparatus for manufacturing an exemplary direct carbonation method of the present invention is described. Specifically, it comprises: a slag feeding device (slag feeder) 100 for injecting slag; a carbonation reactor 200 for performing a carbonation reaction; an absorption section 300 including an absorption tower 301 for increasing the solubility of liquid CO2 to promote the carbonation reaction; and a conveying section 400 for conveying the slag after the carbonation reaction has been completed, wherein a portion of the conveying section may include a cleaning section 500 for cleaning the reaction using water.

[0057] The slag feeding device (slag feeder) 100 is a device for conveying slag filled into the hopper 101 at the top of the carbonation reactor 200, and can be in the form of a spiral or a conveyor belt. Figure 2 The slag feeding section 102 can be configured in various forms, including (B) and (C). The slag feeding device is used to control the amount of slag injected into the upper part of the carbonation reactor.

[0058] The carbonation reactor 200 is a batch reactor, with NaHCO3 solution fed from the top to the bottom. The total reaction time can be controlled according to the liquid flow rate. NaHCO3 flows along the slag surface, thus carrying out the mineral carbonation reaction on the slag surface. The carbonation reactor can be controlled using a vibrating pad or impact device to ensure smooth powder transport.

[0059] The absorption tower 301 of the absorption section 300 is the part that absorbs CO2 through an acid-base reaction. In the upper part, NaOH solution is injected from the top to the bottom through a spray nozzle, for example. The gas containing CO2 moves from the bottom to the top of the absorption tower. In this process, CO2 is absorbed through the cross reaction between liquid and gas, and waste gas without CO2 is discharged.

[0060] The conveying section 400 allows the slag to react with the NaHCO3 solution during transport, carrying out further mineral carbonation, thereby increasing the reaction time. The slag that has completed the mineral carbonation reaction can be recovered and reused in the hopper 30 at the lower end of the conveying section. At this time, the conveying section 400 can be in a spiral configuration (A) or a conveyor belt configuration (…). Figure 2 , B) constitutes.

[0061] Figure 1 The illustration schematically shows the configuration of an exemplary CO2 capture and continuous direct mineral carbonation reactor of the present invention, in which the batch reactor 200 is linked with the slag feeding section 102 and the conveying section 400 of the spiral configuration A. Figure 2 This refers to the case where the batch reactor 200 is linked with the slag feeding section 102 and the conveying section 400 in conveyor belt form B.

[0062] 2. Continuous mineral carbonation process using direct carbonation method As a simulation experiment of the continuous mineral carbonation reaction of the direct carbonation method of the present invention, 50g of steelmaking slag were injected into either a 1M NaHCO3 solution (CO2 loading 100%) or a mixed solution of 0.75M NaHCO3 and 0.25M NaOH (CO2 loading 75%) in a 500ml Erlenmeyer flask, and the CO2 absorption was measured over time.

[0063] As the reaction proceeds, alkaline earth metals in the slag deposit in solid form, thus reducing the total inorganic carbon (TIC) in the liquid phase. Therefore, the reduction in TIC relative to the initial TIC can be calculated as the amount of CO2 absorbed by the slag. Over time, the reaction between the slag and CO2 gradually slows down; the point at which the reaction ceases is considered the maximum CO2 absorption capacity of the slag.

[0064] like Figure 3 It can be confirmed that the mineral carbonation reaction time of slag can vary depending on the particle size / NaHCO3 concentration. In particular, for slag with a particle size of less than 0.075 mm, by controlling the reaction rate of steelmaking slag to 3 hours, it has been confirmed that over 85% mineral carbonation conversion can be achieved. Therefore, by applying the continuous direct mineral carbonation apparatus according to the present invention, the reaction residence time can be ensured to a maximum of approximately 3 hours, allowing the slag to react effectively with CO2. Furthermore, since the continuous mineral carbonation reaction occurs in parallel flow contact within the carbonation reactor, the residence time can be controlled by adjusting the rates of the solid and liquid phases, thereby activating the mineral carbonation reaction by increasing the contact time.

[0065] [Table 1] The CO2 conversion rate and CO2 absorption in Table 1 are calculated in the following way.

[0066] 1) CO2 conversion rate CO2 conversion rate was measured three times using an Analytica multi NC / 3100 analyzer from Jena Analytical Instruments, and three values ​​with a reproducibility of less than 1% were selected.

[0067] 2) CO2 absorption CO2 absorption is calculated based on the following formula (4).

[0068] Equation (4) 3. Confirmation of pH changes and CO2 absorption rate (%) over time during continuous mineral carbonation reactions using direct carbonation. (1) Continuous mineral carbonation using direct carbonation of blast furnace slag 50 g of slag was added to a 0.75 mol (H2O standard) NaHCO3 aqueous solution, and the pH change and CO2 absorption rate (%) were measured over time. The CO2 absorption rate (%) was then calculated using the following formula (5).

[0069] Equation (5) As a result, OH is generated as the reactions in equations (1) and (2) below proceed. - Therefore, as Figure 4 As shown in (a), the increase in pH within the liquid phase was confirmed.

[0070] NaHCO3→Na + +HCO3 - Reaction formula (1) CaO + HCO3 - →CaCO3+OH - Reaction formula (2) In addition, as Figure 4 As can be confirmed in (b), as the reaction proceeds, the increase in CO2 absorption capacity, i.e., absorption rate, gradually decreases until it reaches a range where no further reaction occurs. Therefore, the reaction time according to the present invention is preferably within 5 hours, for example, within 3 hours or within 2 hours.

[0071] (2) Continuous mineral carbonation using direct carbonation of KR slag Using the same process as described in (1), but replacing the slag with hot metal pretreatment slag (KR slag), the pH change and CO2 absorption rate (%) over time were measured and shown. Figure 5 In this paper, based on particle size differences, the CO2 uptake (gCO2 / kg_slag) according to pH changes is plotted as follows: Figure 6 middle.

[0072] [Explanation of reference numerals in the attached figures] 10: Flow meter; 20: Pump 30: Slag feed bucket; 40: H2O tank 100: Slag feeding device (slag feeder) 101: Hopper; 102: Slag Feeding Section 110: Gas inlet section; 120: Gas outlet section 200: Carbonation reactor 300: Absorption section 301: Absorption tower; 302: Demister 303: Injection nozzle; 304: Line mixer 305: Mass Flow Meter (MFC) 400: Conveying Department 500: Cleaning Department A: Spiral shape B: Conveyor belt form

Claims

1. A continuous mineral carbonation apparatus, comprising: An absorption tower that uses an alkaline absorbent to absorb CO2 from waste gas containing CO2, discharges purified waste gas, and discharges CO2-containing absorbent. A slag feeding device that feeds industrial byproducts containing calcium oxide (CaO) into a carbonation reactor; A carbonation reactor, wherein the carbonation reaction occurs between the CO2-containing absorbent discharged from the absorber and an industrial byproduct containing calcium oxide (CaO); and A conveying section continuously conveys the mixture discharged from the carbonation reactor to a storage section.

2. The continuous mineral carbonation apparatus according to claim 1, wherein, The alkaline absorbent is selected from at least one of sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), and potassium carbonate (K2CO3).

3. The continuous mineral carbonation apparatus according to claim 1, wherein, The alkaline absorbent is an aqueous solution of sodium hydroxide (NaOH), and the CO2-containing absorbent is an aqueous solution of sodium bicarbonate (NaHCO3).

4. The continuous mineral carbonation apparatus according to claim 1, wherein, The industrial byproduct containing calcium oxide is selected from at least one of the following: at least one slag selected from steelmaking slag, blast furnace slag and iron pretreatment slag; fly ash; fly ash; cement kiln ash; and dust from chlorine bypass systems.

5. The continuous mineral carbonation apparatus according to claim 1, wherein, The particle size of the industrial by-product containing calcium oxide is greater than 0.001 mm and less than 0.6 mm or less than 0.075 mm.

6. The continuous mineral carbonation apparatus according to claim 1, wherein, The slag feeding device includes: a hopper, the hopper including a receiving space for containing industrial by-products containing calcium oxide; and a slag feeding section disposed at the lower end of the hopper, which continuously feeds the industrial by-products containing calcium oxide discharged from the hopper into the carbonation reactor.

7. The continuous mineral carbonation apparatus according to claim 6, wherein, The slag feeding section continuously feeds industrial byproducts containing calcium oxide into the carbonation reactor via a spiral or conveyor belt.

8. The continuous mineral carbonation apparatus according to claim 1, wherein, The conveying section, in the form of a spiral or conveyor belt, continuously transports the mixture discharged from the carbonation reactor to the storage section.

9. The continuous mineral carbonation apparatus according to claim 1, wherein, The continuous mineral carbonation apparatus further includes a cleaning section for cleaning the mixture discharged from the carbonation reactor and conveyed by the conveying section.

10. A continuous mineral carbonation method, comprising using the continuous mineral carbonation apparatus according to any one of claims 1 to 9, and including the following steps: The CO2 in the waste gas containing CO2 is absorbed by an alkaline absorbent solution, the purified waste gas is discharged, and a CO2-containing absorbent solution is prepared. The CO2-containing absorbent is mixed with an industrial byproduct containing calcium oxide (CaO) to carry out a carbonation reaction; and The mixture discharged as a result of the carbonation reaction is continuously transported and stored.

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