Carbon recycling system

Abstract

To provide a carbon recycling system capable of fixing carbon dioxide by using a calcium source, recovering the carbon dioxide in the form of a calcium carbonate, putting the recovered calcium carbonate on a commercial stream, and securing a profit for covering a cost for going through each process.SOLUTION: A carbon recycling system utilizes carbon dioxide by performing at least the following (A) to (C) as essential means. (A) reaction means of a calcium source and carbon dioxide for producing calcium carbonate by reaction of the calcium source and carbon dioxide, (B) calcium carbonate conveying means for conveying the calcium carbonate, (C) calcium carbonate utilization means for utilizing the conveyed calcium carbonate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a carbon recycling system that fixes carbon dioxide by carbonation using a calcium source and recovers the carbon dioxide in the form of calcium carbonate. The present invention also relates to a carbon recycling system that utilizes the calcium carbonate as carbon dioxide-derived products (valuable materials), such as a cement admixture, a concrete admixture, and a soil improvement material. [Background technology]

[0002] According to a report by the Ministry of Economy, Trade and Industry (Agency for Natural Resources and Energy), the amount of carbon dioxide emitted during cement production in 2019 was 41.47 million tons, accounting for approximately 4% of Japan's total carbon dioxide emissions. If the amount of carbon dioxide emitted during cement production (approximately 4%) is taken as 100%, the proportion of carbon dioxide derived from raw materials such as limestone is approximately 60%, and the proportion of carbon dioxide derived from fossil fuels used to burn cement clinker is approximately 30% (Non-Patent Document 1).

[0003] In response to this situation, the cement industry has recently been working hard to develop carbon recycling technology, which is one form of carbon neutrality. Carbon recycling here refers to a technology that not only reduces carbon dioxide emissions during cement production, but also treats carbon dioxide as a resource and utilizes its fixation products (calcium carbonate, etc.) (Non-Patent Document 1).

[0004] Specifically, the carbon recycling system described above is a circulation system that fixes and captures carbon dioxide by repeating the following steps (a) to (c). Steps (a) to (c) are listed below along with related literature. (a) A process for separating and recovering carbon dioxide from exhaust gas generated during the production of cement clinker. With regard to the above step (a), Patent Document 1 proposes a method for separating and recovering carbon dioxide, which includes a step of contacting a gas containing carbon dioxide with an absorption liquid containing a carbon dioxide-absorbing amine compound, an alkylene urea compound, and water to separate the carbon dioxide, and a step of recovering the carbon dioxide from the absorption liquid that has absorbed the carbon dioxide.

[0005] (b) A step of reacting the recovered carbon dioxide with a calcium source such as calcium hydroxide or cement hydrate in the concrete during the production of concrete to fix the carbon dioxide. With regard to the above step (b), Patent Document 2 proposes a method for producing a cement composition, including the steps of: mixing part of the cement, part or all of the water, and a cement dispersant to obtain a cement-containing kneaded product having a specific water-cement ratio; supplying carbon dioxide gas into the cement-containing kneaded product to obtain a carbonated kneaded product; and kneading the carbonated kneaded product with the remainder of the cement, the remainder of the water, and aggregate to obtain the cement composition.

[0006] (c) A process of fixing carbon dioxide to calcium sources such as calcium hydroxide and cement hydrate in hardened concrete or waste concrete. With regard to the above step (c), Patent Document 3 proposes a method for fixing carbon dioxide, which includes a contacting step of bringing a carbon dioxide-containing gas at 350°C or higher into contact with a cementitious hardened body (concrete or mortar) to fix the carbon dioxide contained in the carbon dioxide-containing gas in the cementitious hardened body. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Ministry of Economy, Trade and Industry, Bureau of Economy, Trade and Industry, Agency for Natural Resources and Energy, "Domestic and international trends toward carbon neutral concrete and cement," published on November 2, 2022 [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2023-142600 [Patent Document 2] Japanese Patent Application Publication No. 2023-136588 [Patent Document 3] Japanese Patent Publication No. 2020-131074 Summary of the Invention [Problem to be solved by the invention]

[0009] However, each of the above steps has the following problems (Non-Patent Document 1): In the above step (a), the issues are the increase in the amount of carbon dioxide recovered and the high recovery costs. In the above step (b), the challenges are maximizing the amount of carbon dioxide fixed by concrete and the high fixation costs. The above-mentioned process (c) has the problems of increasing the amount of calcium source extracted from the concrete, increasing the amount of fixed carbon dioxide, and high extraction costs.

[0010] Further challenges include securing supply and consumption destinations for the carbon dioxide and its fixation products obtained in each of the above processes, and developing new uses for the fixation products. Also, in order to cover the costs required to operate each of the above processes, it is necessary to put the fixation products of carbon dioxide into commercial distribution and secure capital (profits).

[0011] Therefore, an object of the present invention is to provide a carbon recycling system that fixes carbon dioxide using a calcium source, recovers it in the form of calcium carbonate, and puts the recovered calcium carbonate into the commercial stream, thereby ensuring a profit that covers the costs of running each of the above steps. [Means for solving the problem]

[0012] As a result of extensive research into achieving the above object, the present inventors have found that By utilizing at least the following means (A) to (C), the carbon recycling system for utilizing carbon dioxide can utilize carbon dioxide in the form of calcium carbonate that fixes carbon dioxide, and has found that it can also cover the costs of putting the calcium carbonate into the commercial stream, and has completed the inventions [1] to

[10] below.

[0013] [1] A carbon recycling system that utilizes carbon dioxide by utilizing at least the following essential means (A) to (C): (A) a means for reacting a calcium source with carbon dioxide to produce calcium carbonate; (B) a calcium carbonate transport means for transporting the calcium carbonate; and (C) A means for utilizing the transported calcium carbonate. [2] (D) The carbon recycling system according to [1] above, further comprising, as an optional means, a calcium source transfer means for transferring the calcium source produced by the calcium carbonate utilization means to the calcium source and carbon dioxide reaction means. Hereinafter, for the sake of brevity, the above means may be referred to as (A) reaction means, (B) transport means, (C) utilization means, and (D) forwarding means, respectively. [3] (A) The carbon recycling system according to [1] or [2] above, wherein the means for reacting the calcium source with carbon dioxide is a reaction tank in which carbon dioxide is sealed and / or a reaction tank in which carbon dioxide is aerated. [4] The carbon recycling system according to [1] or [2], wherein (B) the means for transporting calcium carbonate and (D) the means for transporting the calcium source are one or more selected from a cement transport vehicle, a cement transport ship, a dump truck, a flatbed truck (a general-purpose truck with a flat bed), a concrete transport vehicle, etc. [5] (C) The carbon recycling system according to [1] or [2] above, wherein the means for utilizing calcium carbonate is one or more selected from cement production, ready-mix concrete production, concrete product production, construction, and ground improvement, etc. [6] The carbon recycling system according to [1] or [2], wherein the calcium source is one or more selected from the group consisting of pre-hardened or hardened fresh concrete sludge, concrete powder, cement, and the like. [7] The carbon recycling system according to [1] or [2], wherein the carbon dioxide is one or more selected from carbon dioxide in exhaust gas from a cement factory and / or a concrete product factory, and carbon dioxide recovered from exhaust gas from a cement factory and / or a concrete product factory. [8] The carbon recycling system according to [1] or [2], wherein the location where the means for reacting the calcium source with carbon dioxide is used is one or more selected from a cement factory, a cement terminal, a ready-mix concrete factory, an on-site plant, a concrete product factory, etc. [9] The carbon recycling system according to [1] or [2], wherein the calcium carbonate in the calcium carbonate transport means is in the form of one or more selected from the group consisting of slurry, powder, mixed cement containing the calcium carbonate as an admixture, and cement-based solidification material containing the calcium carbonate as an admixture.

[10] The carbon recycling system according to [1] or [2], wherein the raw materials and reaction vessels used to produce calcium carbonate in the reaction means of the calcium source and carbon dioxide are provided to users on a subscription basis to generate revenue. [Effects of the Invention]

[0014] The carbon recycling system of the present invention can efficiently recover carbon dioxide in the form of calcium carbonate that fixes carbon dioxide. In addition, by putting this calcium carbonate into the commercial stream, it is possible to obtain the funds to operate each of the above-mentioned steps, and thus commercialize the carbon recycling system. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a conceptual diagram showing an example of a carbon recycling system of the present invention. [Figure 2] 2 is a flowchart showing an example of a carbon recycling system of the present invention, in which calcium carbonate (slurry) produced by reacting concrete, cement, ready-mixed concrete sludge, etc. with CO2 in a carbon dioxide reaction tank is transported in one or more forms selected from slurry, powder, granular material, mixed cement, cement-based solidification material, etc. to one or more locations selected from construction and ground improvement sites, concrete product factories, ready-mixed concrete factories, concrete plants for on-site production, etc., for utilization. [Figure 3] FIG. 1 is a schematic diagram showing an example of a calcium carbonate production apparatus equipped with a reaction vessel in which carbon dioxide is sealed. DETAILED DESCRIPTION OF THE INVENTION

[0016] As shown in FIG. 1, the carbon recycling system of the present invention is a system capable of utilizing carbon dioxide, which includes at least (A) a means for reacting a calcium source with carbon dioxide, (B) a means for transporting calcium carbonate, and (C) a means for utilizing calcium carbonate as essential means, and further includes (D) a means for transporting the calcium source as an optional means. The present invention will be described in detail below for each of the above means.

[0017] (A) Means for reacting a calcium source with carbon dioxide The reaction means is a means for reacting a calcium source with carbon dioxide to produce calcium carbonate, and examples thereof include a reaction tank in which carbon dioxide is sealed (e.g., the carbon dioxide reaction tank in FIG. 3) and / or a reaction tank in which carbon dioxide is aerated.

[0018] (1) Calcium source The calcium source may be one or more selected from the group consisting of fresh concrete sludge, concrete powder, cement, etc. The concrete powder includes powder of waste concrete and concrete product scraps. Of the above calcium sources, ready-mixed concrete sludge, waste concrete and its powder and granular form, and concrete product scraps and its powder and granular form can be traded at a price if they are placed in the commercial stream of the waste disposal industry as one of the waste materials to be treated.

[0019] (2) Carbon dioxide The carbon dioxide may be carbon dioxide contained in exhaust gas from a cement factory, carbon dioxide contained in exhaust gas from a concrete product factory, or carbon dioxide recovered from one or more exhaust gases selected from exhaust gases from a cement factory, concrete product factory, etc. Here, the carbon dioxide recovered from the exhaust gas is, for example, carbon dioxide recovered by a carbon dioxide separation and recovery method such as an amine method, and is preferred because it has a higher concentration and purity than carbon dioxide in exhaust gas, thereby improving the reaction efficiency between the calcium source and carbon dioxide. The exhaust gases from cement plants mainly consist of final exhaust gases, boiler exhaust gases, and heavy machinery exhaust gases, while the exhaust gases from concrete product plants mainly consist of boiler exhaust gases and heavy machinery exhaust gases.

[0020] (3) Reaction of a calcium source with carbon dioxide An example of a mode in which the calcium source reacts with carbon dioxide to produce calcium carbonate is when cement, which is a calcium source, is mixed with water to prepare a cement hydrate slurry, and then the cement hydrate in the slurry comes into contact with carbon dioxide to produce calcium carbonate. Examples of the "contact" include a mode in which the cement hydrate comes into contact with carbon dioxide saturated in a reaction tank, and a mode in which carbon dioxide is aerated (bubbled) into the slurry in a reaction tank, or aerated and stirred.

[0021] In the step of generating calcium carbonate, carbon dioxide is preferably supplied so that the pH of the carbonated cement hydrate slurry becomes 5.0 to 11.5. If the pH of the slurry is in the above range, the content of carbon dioxide in the slurry becomes 100 to 350 kg in terms of carbon dioxide per ton of cement, which is preferable because the amount of fixed carbon dioxide increases.

[0022] In the step of producing calcium carbonate, it is preferable to fix 80% or more of the carbon dioxide supplied. If the amount of fixed carbon dioxide is 80% or more, the fixation efficiency of carbon dioxide is high, which contributes to reducing carbon dioxide.

[0023] (4) Form of calcium carbonate The calcium carbonate may be in the form of a slurry or powder. A slurry is low cost because it does not require subsequent drying or granulation, while a powder can be reduced in volume compared to a slurry and is easier to handle. The drying method for the slurry may be one or more selected from natural drying, hot air drying, vacuum drying, cooling drying, infrared drying, freeze drying, and contact drying. The drying method described above allows drying without decarbonating the carbon dioxide fixed in the calcium carbonate. Furthermore, if the heat of the exhaust gas is used for part or all of the heat used in the drying, thermal energy can be reduced.

[0024] Furthermore, to improve handling and utilization convenience, such as by suppressing dust, the calcium carbonate powder may be granulated. The granulation device may be one or more selected from a pan pelletizer, a pan mixer, an agitator granulator, a briquetting machine, a roll press, an extruder, etc. During granulation, one or more excipients selected from bentonite, cement, a solidifying agent, a thickener, etc. may be added to improve formability.

[0025] (5) Calcium carbonate manufacturing site The production can be carried out by installing a reaction tank capable of sealing the carbon dioxide (for example, the calcium carbonate production facility shown in FIG. 3) and / or a reaction tank for aerating the carbon dioxide in one or more locations selected from cement factories, cement terminals, ready-mix concrete factories, on-site plants, concrete product factories, etc. At these locations, exhaust gas containing carbon dioxide is constantly generated, so if the exhaust gas is collected near the source of generation (in situ collection method), transportation of the exhaust gas containing carbon dioxide is not necessary and the efficiency of carbon dioxide fixation is significantly improved, which is preferable. An on-site plant is a plant located at a construction site where cement, concrete, etc. are used for construction and ground improvement work.

[0026] Furthermore, the present invention may involve selling the calcium source and calcium carbonate to one or more cement plants, cement terminals, ready-mixed concrete plants, on-site plants, concrete product plants, etc., and may also involve providing (renting or installing) on a subscription basis a reaction tank that seals carbon dioxide and / or a reaction tank that aerates carbon dioxide, which are means for reacting the calcium source with carbon dioxide. Here, subscription refers to a business model in which a fee is paid periodically on a monthly or yearly basis. This will enable the acquisition of funds to run each of the above processes, improving the business viability of the carbon recycling system.

[0027] (B) Calcium carbonate transport means The transport means may be one or more selected from cement transport vehicles such as cement pumping vehicles, cement transport ships, dump trucks, flatbed trucks, and concrete transport vehicles such as concrete agitator vehicles. Of these, the cement transport vehicles and cement transport ships are suitable for transporting calcium carbonate powder or granulated material, and the concrete transport vehicles are suitable for transporting calcium carbonate slurry. For example, when ready-mixed concrete sludge is carbonated and utilized as a concrete admixture at a ready-mixed concrete plant, the ready-mixed concrete sludge can be transported from the ready-mixed concrete plant to a cement manufacturing plant in a concrete transport vehicle, carbonated using the plant's exhaust gas, and then the carbonated ready-mixed concrete sludge slurry can be transported as return cargo from the cement manufacturing plant to the ready-mixed concrete plant, thereby improving the efficiency of transportation and delivery.

[0028] (C) Utilization of calcium carbonate The utilization means is one or more selected from cement production, ready-mix concrete production, concrete product production, construction, ground improvement, etc. Calcium carbonate can be used as a cement admixture and a cement-based solidification admixture in cement production, as a concrete admixture in ready-mix concrete production and concrete product production, and as an auxiliary material added at construction and ground improvement sites. Furthermore, by utilizing calcium carbonate and putting it into the commercial stream as a valuable commodity, it is possible to obtain the capital necessary to operate each of the above-mentioned means.

[0029] (D) Means of transporting calcium sources The above-mentioned transport means, like the (B) transport means already described, can be one or more types selected from cement transport vehicles, cement transport ships, concrete transport vehicles, etc., as well as dump trucks, flatbed trucks, and other bulk transport vehicles. The calcium source to be transferred is concrete sludge generated from ready-mixed concrete plants, concrete product plants, construction sites, etc., and concrete powder and granules, etc., and is a cement hydrate containing calcium hydroxide and cement hydrate, etc. The calcium source is generated in (C) the utilization means and has a relatively low hydration activity. The calcium source is transferred to (A) the reaction means. [Example]

[0030] Examples of utilization (applications) of calcium carbonate in the present invention will be specifically described below as examples, but the present invention is not limited to these examples. 1. Example of use as a bleeding-reducing material (admixture for concrete) (1) Materials used The materials used are shown in Table 1.

[0031] [Table 1]

[0032] (2) Manufacturing of bleeding reduction material (calcium carbonate) Ten batches (10 batches) of cement slurry were prepared by mixing 10 kg of ordinary Portland cement and 30 kg of tap water for 120 seconds using a hand mixer. The temperature of the slurry was 23°C (ambient temperature was 20°C). Next, using the apparatus shown in Figure 3, the cement slurry was circulated between a carbon dioxide reaction tank filled with carbon dioxide gas and a slurry tank using a pump for 8 hours to carbonate the cement hydrate in the slurry and obtain a calcium carbonate slurry. The pH of the calcium carbonate slurry thus obtained was 8.0, and the ratio of carbon dioxide fixed by the cement hydrate slurry to the amount of carbon dioxide supplied was 95%. Next, the supernatant water of the calcium carbonate slurry was removed by decantation, and the residue was air-dried at 30°C for 3 days and pulverized to obtain a powder with a Blaine specific surface area of 13550 cm 2 / g of a bleeding reducer (abbreviated as BR) was produced.

[0033] Next, thermogravimetry-differential thermal analysis (TG-DTA) of the bleeding-reducing material was performed. From the measurement results, the mass decrease in the endothermic peak range around 550 to 800°C was attributed to the decarbonation of calcium carbonate contained in the bleeding-reducing material, and this decrease was considered to be the amount of fixed carbon dioxide. Therefore, the carbon dioxide content (fixed ratio) in the bleeding-reducing material was 214 kg per ton of cement used.

[0034] (3) Manufacturing concrete containing bleeding-reducing additives Concrete containing the above-mentioned bleeding-reducing additive was produced according to the mix proportions shown in Table 2 below and in accordance with JIS A 1138 "Laboratory concrete production method."

[0035] (4) Calculation of the mass ratio of the carbon dioxide content in concrete to the cement content in concrete (i.e., the amount of fixed carbon dioxide in concrete), the amount of bleeding, and measurement of compressive strength (i) Calculation of the amount of carbon dioxide fixed in concrete The specimens were crushed to remove the coarse aggregate, and then thermogravimetric-differential thermal analysis (TG-DTA) was performed on the mortar portion excluding the coarse aggregate. From the measurement results, the mass loss in the endothermic peak range of approximately 550 to 800°C was attributed to the decarbonation of calcium carbonate contained in the mortar portion, and this loss was measured as the amount of carbon dioxide. The amount of carbon dioxide fixed (percentage content) per ton of the cement in the carbonate and the cement used to mix the concrete was then calculated. The results are shown in Table 2.

[0036] (ii) Measurement of the amount of bleeding and compressive strength of concrete The bleeding amount of the concrete was measured in accordance with JIS A 1123, "Testing method for bleeding of concrete." The compressive strength of the concrete was measured in accordance with JIS A 1108, "Testing method for compressive strength of concrete," using concrete specimens that had been cured underwater for 28 days. The results are shown in Table 2.

[0037] [Table 2]

[0038] As shown in Table 2, Examples 1 to 5 of the present invention all have a smaller amount of bleeding and higher compressive strength than Comparative Examples 1 and 2. Also, as shown in Table 2, Examples 1 to 5 of the present invention all have a higher compressive strength than Comparative Example 3. Therefore, the calcium carbonate obtained by the present invention has commercial value as a bleeding reducing material.

[0039] 2. Example of hydraulic composite (admixture for concrete) (1) Materials used The materials used are shown in Table 1 above.

[0040] 2. Preparation of carbonated cement hydrate (calcium carbonate) slurry Ten batches (10 batches) of cement hydrate slurry were prepared by kneading 10 kg of ordinary Portland cement and 30 kg of tap water for 120 seconds using a hand mixer. The temperature of the slurry was 23°C (ambient temperature: 20°C). Next, as shown in Figure 3, the cement hydrate slurry was circulated using a pump between a carbon dioxide reaction tank filled with carbon dioxide gas and a slurry tank, thereby carbonated the cement hydrate in the slurry until the pH of the slurry reached a predetermined value. Next, the carbonated cement hydrate (calcium carbonate) slurry was left to stand for one day in an environment of 20°C, and the supernatant water was decanted off to produce a carbonated cement hydrate slurry with a water / carbonated cement hydrate (cement equivalent) ratio [W2 / C2 in Table 4] of 100%. The physical properties (pH and viscosity) of the carbonated cement hydrate slurry thus obtained are shown in Table 3. The temperature of the carbonated cement hydrate slurry during viscosity measurement was 21°C (ambient temperature: 20°C).

[0041] [Table 3]

[0042] The pH and viscosity of the carbonated cement hydrate slurries in the Examples and Comparative Examples in Table 3 are as follows: That is, the pH of Examples 1 to 9 was 6.83 to 10.10, and the viscosity was 1.60 to 4.23 mPa·s. In comparison, the viscosity of Comparative Example 2 was 1.40 mPa·s, which was similar to that of the Examples, but the pH was 11.10, which was higher than that of the Examples. Conversely, the pH of Comparative Example 3 was 8.94, which was similar to that of the Examples, but the viscosity was 7.21 mPa·S, which was higher than that of the Examples.

[0043] (2) Manufacturing of concrete (hydraulic composites) Concrete was produced in accordance with JIS A 1138 "Laboratory concrete production" according to the blending ratios shown in Table 4. That is, in Examples 1 to 9 and Comparative Examples 2 and 3, concrete was produced by mixing carbonated cement hydrate slurry according to the blending ratios shown in Table 4, while in Comparative Example 1, concrete was produced using only cement without using the carbonated cement hydrate slurry.

[0044] (3) Measurement of concrete slump flow and compressive strength The slump flow of the concrete was measured in accordance with JIS A 1150, "Testing Method for Slump Flow of Concrete." The compressive strength of the concrete was measured in accordance with JIS A 1108, "Testing Method for Compressive Strength of Concrete," using concrete specimens that had been cured underwater for ages of 3, 28, and 91 days. The results are shown in Table 4.

[0045] [Table 4]

[0046] As shown in Table 4, Examples 1 to 9 of the present invention all have higher compressive strengths in the short term (3 days old), medium term (28 days old), and long term (91 days old) and have larger slump flows than Comparative Examples 1 to 3. Therefore, the hydraulic composite using the calcium carbonate obtained by the present invention as a concrete admixture has improved strength and fluidity, opening up new uses for calcium carbonate. Furthermore, since the calcium carbonate absorbs and fixes carbon dioxide, it contributes to reducing carbon dioxide emissions.

Claims

1. A carbon recycling system that utilizes carbon dioxide by utilizing at least the following (A) to (C) as essential means. (A) a means for reacting a calcium source with carbon dioxide to produce calcium carbonate; (B) a calcium carbonate transport means for transporting the calcium carbonate; and (C) A calcium carbonate utilization means for utilizing the transported calcium carbonate.

2. (D) The carbon recycling system according to claim 1, further comprising a calcium source transfer means as an optional means for transferring the calcium source produced by the calcium carbonate utilization means to the calcium source and carbon dioxide reaction means.

3. 3. The carbon recycling system according to claim 1 or 2, wherein (A) the means for reacting the calcium source with carbon dioxide is a reaction tank in which carbon dioxide is sealed and / or a reaction tank in which carbon dioxide is aerated.

4. 3. The carbon recycling system according to claim 1, wherein the (B) calcium carbonate transport means and the (D) calcium source transport means are one or more vehicles selected from a cement transport vehicle, a cement transport ship, a dump truck, a flatbed truck, a concrete transport vehicle, and the like.

5. (C) The carbon recycling system according to claim 1 or 2, wherein the means for utilizing calcium carbonate is one or more selected from cement production, ready-mix concrete production, concrete product production, construction, ground improvement, and the like.

6. 3. The carbon recycling system according to claim 1, wherein the calcium source is at least one selected from the group consisting of pre-hardened or hardened fresh concrete sludge, concrete powder and granules, cement, and the like.

7. 3. The carbon recycling system according to claim 1 or 2, wherein the carbon dioxide is one or more selected from carbon dioxide in exhaust gas from a cement factory and / or exhaust gas from a concrete product factory, and carbon dioxide recovered from exhaust gas from a cement factory and / or exhaust gas from a concrete product factory.

8. 3. The carbon recycling system according to claim 1, wherein the location where the means for reacting the calcium source with carbon dioxide is used is one or more selected from a cement plant, a cement terminal, a ready-mix concrete plant, an on-site plant, a concrete product plant, and the like.

9. 3. The carbon recycling system according to claim 1, wherein the calcium carbonate in the calcium carbonate transport means is in the form of one or more selected from the group consisting of a slurry, a powder, a mixed cement containing the calcium carbonate as an admixture, and a cement-based solidification material containing the calcium carbonate as an admixture.

10. 3. The carbon recycling system according to claim 1 or 2, wherein the means for reacting the calcium source with carbon dioxide provides raw materials and reaction vessels used to produce calcium carbonate to users on a subscription basis to generate revenue.

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