Carbon dioxide fixation method

Abstract

To provide a method for efficiently fixing carbon dioxide generated in a steelmaking process by using blast furnace slag generated in the steelmaking process.SOLUTION: A carbon dioxide fixation method comprises the steps of preparing a composition comprising water, blast furnace slag, an amine-based compound, and an additive, stirring the composition to elute calcium from the blast furnace slag, and bringing the composition from which calcium has been eluted into contact with air to fix carbon dioxide contained in the air.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for fixing carbon dioxide. [Background technology]

[0002] Japan emits 1,064 million tons of carbon dioxide (CO2) per year. Of the total carbon dioxide emissions, emissions from the industrial sector account for approximately 27%. Of the total carbon dioxide emissions from the industrial sector, emissions from the steel industry in particular account for approximately 39%. In order to reduce embodied carbon in buildings, it is extremely important to reduce carbon dioxide emissions from steel manufacturing.

[0003] Furthermore, in the steel manufacturing process, steel slag is generated as a by-product during the refining process, which removes impurities from pig iron. Steel slag is broadly divided into blast furnace slag and steelmaking slag. Blast furnace slag and steelmaking slag are further classified according to the cooling method and type of furnace. The amount of blast furnace slag produced is approximately twice that of steelmaking slag. Therefore, capturing the carbon dioxide generated in the steelmaking process and absorbing and fixing it in blast furnace slag is an effective approach from the perspective of reducing carbon dioxide emissions from steel and adding value.

[0004] As a technique for recovering carbon dioxide generated in the steelmaking process and absorbing and fixing it in blast furnace slag or the like, for example, the technique described in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-214262 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method described in Patent Document 1 was unable to efficiently fix carbon dioxide generated in the steelmaking process using blast furnace slag generated in the steelmaking process.

[0007] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a carbon dioxide fixation method that can efficiently fix carbon dioxide generated in the steelmaking process by using blast furnace slag generated in the steelmaking process. [Means for solving the problem]

[0008] The present invention has the following aspects. [1] preparing a composition containing water, blast furnace slag, an amine compound, and an additive; agitating the composition to dissolve calcium from the blast furnace slag; and bringing atmospheric air into contact with the composition from which calcium has been eluted, thereby immobilizing carbon dioxide contained in the atmospheric air. [2] The carbon dioxide fixation method according to [1], wherein the additive is at least one selected from hydrochloric acid, ethylenediaminetetraacetic acid, and cement. [3] The carbon dioxide fixation method according to [1] or [2], wherein the amine compound is at least one selected from 2-amino-2-methyl-1-propanol, 2-(methylamino)ethanol, and N-methyldiethanolamine. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a carbon dioxide fixation method that can efficiently fix carbon dioxide generated in the steelmaking process by using blast furnace slag generated in the steelmaking process. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a graph showing the relationship between the type of amine compound and the amount of calcium carbonate produced in Experimental Example 1. [Figure 2]FIG. 2 is a graph showing the relationship between the calcium ion concentration in the liquid phase of the composition after calcium elution and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production) in Experimental Example 1. [Figure 3] FIG. 10 is a graph showing the relationship between the type of amine compound and the amount of calcium carbonate produced in Experimental Example 2. [Figure 4] FIG. 1 is a graph showing the relationship between the calcium ion concentration in the liquid phase of the composition after calcium elution and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production) in Experimental Example 2. [Figure 5] FIG. 10 is a graph showing the relationship between the type of amine compound and the amount of calcium carbonate produced in Experimental Example 3. [Figure 6] FIG. 10 is a graph showing the relationship between the calcium ion concentration in the liquid phase of the composition after calcium elution and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production) in Experimental Example 3. [Figure 7] FIG. 10 is a graph showing the relationship between the type of amine compound and the amount of calcium carbonate produced in Experimental Example 4. [Figure 8] FIG. 10 is a graph showing the relationship between the calcium ion concentration in the liquid phase of the composition after calcium elution and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production) in Experimental Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Carbon dioxide fixation method] A carbon dioxide fixation method according to one embodiment of the present invention includes the steps of preparing a composition containing water, blast furnace slag, an amine, and an additive (hereinafter referred to as the "first step"), stirring the composition to leach calcium from the blast furnace slag (hereinafter referred to as the "second step"), and bringing the composition from which calcium has been leached into contact with atmospheric air to fix carbon dioxide contained in the atmosphere (hereinafter referred to as the "third step").

[0012] "First step" In the first step, a composition containing water, blast furnace slag, an amine compound, and an additive is prepared.

[0013] The blast furnace slag used is that generated during the steel refining process.

[0014] The water content relative to the total mass of the composition is preferably 50% by mass or more and 99% by mass or less, more preferably 60% by mass or more and 97% by mass or less, and even more preferably 70% by mass or more and 95% by mass or less. When the water content is equal to or greater than the lower limit, the elution of calcium from blast furnace slag can be promoted. When the water content is equal to or less than the upper limit, the amount of blast furnace slag becomes relatively large, and the amount of calcium in the system can be increased.

[0015] The content of blast furnace slag relative to the total mass of the composition is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less. When the content of blast furnace slag is equal to or greater than the lower limit, a large amount of calcium can be eluted from the blast furnace slag. When the content of blast furnace slag is equal to or less than the upper limit, the amount of water in the powder increases, and the calcium elution rate can be increased.

[0016] Examples of the amine compounds include aliphatic amines and aromatic amines. As the amine compound, an aliphatic amine is preferred because it is easily soluble in water. Examples of the aliphatic amine include alkylamines and alkanolamines. Examples of alkylamines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, and butylamine. Examples of alkanolamines include monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), monoisopropanolamine (MIPA), diisopropanolamine (DIPA), triisopropanolamine (TIPA), N-methylethanolamine (MMEA), and N-methyldiethanolamine (MDEA).

[0017] The amine compound may be any of a primary amine, a secondary amine, a tertiary amine, and a quaternary ammonium salt, and may have a cyclic structure. In addition to the above, examples of amine compounds include 2-amino-2-methyl-1-propanol (AMP), 2-(methylamino)ethanol (MAE), N-methyldiethanolamine (MDEA), dicyclohexylamine (DCHA), dimethylcyclohexylamine (DMCHA), polyetheramine (PEA), diglycolamine (DGA), 2-amino-2-methyl-1-propanol (AMP90), n-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), pyrrolidine, piperidine, piperazine, morpholine, etc. Among these amine compounds, 2-amino-2-methyl-1-propanol (AMP), 2-(methylamino)ethanol (MAE), and N-methyldiethanolamine (MDEA) are preferred. These amine compounds may be used alone or in combination of two or more.

[0018] The content of the amine compound relative to the total mass of the composition is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less. When the content of the amine compound is equal to or more than the lower limit, the rate of fixation of carbon dioxide by the amine compound can be increased. When the content of the amine compound is equal to or less than the upper limit, an increase in the viscosity of the solution due to the amine compound can be prevented.

[0019] Examples of additives include hydrochloric acid, ethylenediaminetetraacetic acid (EDTA), and cement. These additives may be used alone or in combination of two or more.

[0020] When hydrochloric acid is used as an additive, the content of hydrochloric acid relative to the total mass of the composition is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less. When the content of hydrochloric acid is equal to or more than the lower limit, the amount of calcium eluted from the blast furnace slag can be increased. When the content of hydrochloric acid is equal to or less than the upper limit, re-dissolution of precipitated calcium carbonate can be prevented.

[0021] When ethylenediaminetetraacetic acid is used as an additive, the content of ethylenediaminetetraacetic acid relative to the total mass of the composition is preferably 0.5% by mass to 10% by mass, more preferably 1.0% by mass to 8% by mass, and even more preferably 3.0% by mass to 5.0% by mass. When the content of ethylenediaminetetraacetic acid is equal to or greater than the lower limit, the amount of calcium eluted from blast furnace slag can be increased. When the content of ethylenediaminetetraacetic acid is equal to or less than the upper limit, re-dissolution of precipitated calcium carbonate can be prevented.

[0022] When cement is used as an additive, examples of cement include ordinary Portland cement, high-early-strength Portland cement, and moderate-heat Portland cement.

[0023] When cement is used as an additive, the content of cement relative to the total mass of the composition is preferably 0.5% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 10% by mass or less. When the content of cement is equal to or more than the lower limit, the amount of calcium eluted from the blast furnace slag can be increased. When the content of cement is equal to or less than the upper limit, carbon dioxide can be prevented from being adsorbed onto calcium hydroxide derived from the cement.

[0024] "Second step" In the second step, the composition is stirred to dissolve calcium from the blast furnace slag. The stirring time of the composition is preferably 2 hours or more, more preferably 6 hours or more, and even more preferably 12 hours or more. When the stirring time of the composition is equal to or more than the lower limit, calcium can be sufficiently eluted from the blast furnace slag.

[0025] In the second step, when the composition is stirred, the temperature of the composition is preferably 5°C or higher and 95°C or lower, more preferably 10°C or higher and 80°C or lower, and even more preferably 15°C or higher and 70°C or lower. When the temperature at which the composition is stirred is equal to or higher than the lower limit, calcium can be sufficiently eluted from the blast furnace slag. When the temperature at which the composition is stirred is equal to or higher than the lower limit, calcium can be sufficiently eluted from the blast furnace slag.

[0026] "Third step" In the third step, the composition containing eluted calcium is brought into contact with the atmosphere to immobilize carbon dioxide contained in the atmosphere. That is, the eluted calcium reacts with carbon dioxide to produce calcium carbonate (CaCO3), which immobilizes the carbon dioxide.

[0027] In the third step, the method for bringing the composition into contact with the air is not particularly limited, but for example, a method can be used in which the air is blown into the composition while stirring the composition.

[0028] The composition with immobilized carbon dioxide is subjected to solid-liquid separation by a separation method such as centrifugation. The precipitate obtained by solid-liquid separation is subjected to thermogravimetric analysis (TGA) to quantify the amount of calcium carbonate (CaCO3) produced. This makes it possible to quantify the amount of immobilized carbon dioxide.

[0029] According to the carbon dioxide fixation method of this embodiment, calcium carbonate can be efficiently produced by using an additive to promote the elution of calcium ions from blast furnace slag and further promoting the reaction of the eluted calcium ions with carbon dioxide using an amine compound. That is, carbon dioxide generated in the steelmaking process can be efficiently fixed using blast furnace slag generated in the steelmaking process, thereby reducing the amount of carbon dioxide emitted from the steelmaking process. Furthermore, by simultaneously promoting the elution of calcium ions and the fixation of carbon dioxide, calcium carbonate can be efficiently produced. [Example]

[0030] The present invention will be explained in more detail below by way of experimental examples, but the present invention is not limited to the following experimental examples.

[0031] [Experimental Example 1] A composition containing water, ground granulated blast furnace slag (BFS), and an amine compound was prepared. The total volume of the composition was 300 mL, and the mass of the powder contained in the composition was 30 g. The concentration of the amine compound was 1 mol / L. As the amine compounds, three types were used: 2-amino-2-methyl-1-propanol (AMP), 2-(methylamino)ethanol (MAE), and N-methyldiethanolamine (MDEA). Next, the composition was stirred at 20°C for 24 hours using a magnetic stirrer as a stirring device to elute calcium from the ground granulated blast furnace slag. Next, they investigated whether carbon dioxide could be fixed by blowing air containing 5% carbon dioxide into the calcium-eluted composition for 24 hours, causing the eluted calcium to react with carbon dioxide to produce calcium carbonate. The composition into which air had been blown was subjected to solid-liquid separation using a centrifuge. The precipitate obtained by solid-liquid separation was subjected to thermogravimetric analysis (TGA) to quantify the amount of calcium carbonate (CaCO3) produced. This allowed the amount of carbon dioxide immobilized to be quantified. The results are shown in Figure 1. Furthermore, the liquid phase obtained by solid-liquid separation was subjected to inductively coupled plasma atomic emission spectroscopy (ICP-OES / ICP-AES) to measure the calcium ion concentration. The results are shown in Figure 2. Fig. 1 is a diagram showing the relationship between the type of amine compound and the amount of calcium carbonate produced. In Fig. 1, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). Fig. 2 shows the relationship between the calcium ion concentration in the liquid phase of the composition after calcium leaching and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production). In Fig. 2, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). The results shown in Figures 1 and 2 indicate that when only an amine compound was used as an additive, the amount of calcium carbonate produced did not increase compared to the control.

[0032] [Experimental Example 2] A composition was prepared in the same manner as in Experimental Example 1, except that hydrochloric acid was added as an additive. The concentration of hydrochloric acid was set to 0.1 mol / L. Next, in the same manner as in Experimental Example 1, calcium was eluted from the ground granulated blast furnace slag. Next, in the same manner as in Experimental Example 1, air containing 5% carbon dioxide was blown into the composition from which calcium had been eluted for 24 hours. Next, the composition into which air had been blown was subjected to solid-liquid separation. The amount of calcium carbonate (CaCO3) produced in the precipitate obtained by solid-liquid separation was quantified by thermogravimetric analysis (TGA). This allowed the amount of carbon dioxide immobilized to be quantified. The results are shown in Figure 3. Furthermore, the calcium ion concentration of the liquid phase obtained by solid-liquid separation was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES / ICP-AES). The results are shown in Figure 4. Fig. 3 is a diagram showing the relationship between the type of amine compound and the amount of calcium carbonate produced. In Fig. 3, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). Fig. 4 shows the relationship between the calcium ion concentration in the liquid phase of the composition after calcium leaching and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production). In Fig. 4, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). The results shown in Figures 3 and 4 indicate that when an amine compound and hydrochloric acid were used as additives, the amount of calcium carbonate produced increased slightly compared to the control.

[0033] [Experimental Example 3] A composition was prepared in the same manner as in Experimental Example 1, except that ethylenediaminetetraacetic acid (EDTA) was added as an additive. The amount of ethylenediaminetetraacetic acid (EDTA) added was 9.74 g (0.1 mol / L). Next, in the same manner as in Experimental Example 1, calcium was eluted from the ground granulated blast furnace slag. Next, in the same manner as in Experimental Example 1, air containing 5% carbon dioxide was blown into the composition from which calcium had been eluted for 24 hours. Next, the composition into which air had been blown was subjected to solid-liquid separation. The amount of calcium carbonate (CaCO3) produced in the precipitate obtained by solid-liquid separation was quantified by thermogravimetric analysis (TGA). This allowed the amount of carbon dioxide immobilized to be quantified. The results are shown in Figure 5. Furthermore, the calcium ion concentration of the liquid phase obtained by solid-liquid separation was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES / ICP-AES). The results are shown in Figure 6. Fig. 5 is a diagram showing the relationship between the type of amine compound and the amount of calcium carbonate produced. In Fig. 5, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). Fig. 6 shows the relationship between the calcium ion concentration in the liquid phase of the composition after calcium leaching and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production). In Fig. 6, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). The results shown in Figures 5 and 6 indicate that when an amine compound and ethylenediaminetetraacetic acid (EDTA) were used as additives, the amount of calcium carbonate produced did not increase compared to the control. In addition, it was found that the amount of calcium ions eluted in the liquid phase increased.

[0034] [Experimental Example 4] A composition was prepared in the same manner as in Experimental Example 1, except that ordinary Portland cement was added as an additive. The amount of ordinary Portland cement added was 5% of the total powder amount of 30 g. Next, in the same manner as in Experimental Example 1, calcium was eluted from the ground granulated blast furnace slag. Next, in the same manner as in Experimental Example 1, air containing 5% carbon dioxide was blown into the composition from which calcium had been eluted for 24 hours. Next, the composition into which air had been blown was subjected to solid-liquid separation. The amount of calcium carbonate (CaCO3) produced in the precipitate obtained by solid-liquid separation was quantified by thermogravimetric analysis (TGA). This allowed the amount of carbon dioxide immobilized to be quantified. The results are shown in Figure 7. Furthermore, the calcium ion concentration of the liquid phase obtained by solid-liquid separation was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES / ICP-AES). The results are shown in Figure 8. Fig. 7 is a diagram showing the relationship between the type of amine compound and the amount of calcium carbonate produced. In Fig. 7, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). Fig. 8 shows the relationship between the calcium ion concentration in the liquid phase of the composition after calcium elution and the calcium ion concentration in the liquid phase after carbon dioxide fixation (after calcium carbonate production). In Fig. 8, the control is a level where no amine compound was added (a level where the experiment was conducted using only water and ground granulated blast furnace slag). The results shown in Figures 7 and 8 indicate that adding a small amount of cement significantly accelerated carbonation overall, with AMP being the most effective. The amount of calcium carbonate increased by approximately 1.5 times compared to the sample with cement added to AMP and the sample with cement only (no amine added). The reaction increased by approximately 3.5 times compared to the control sample, which contained neither cement nor amine. This is thought to be because the addition of cement effectively broke the glass bonds in the slag, allowing the eluted calcium ions to react with the cement components and form calcium aluminate hydrates and calcium hydroxide (CSH). This further eluted calcium ions from the slag, which reacted effectively with amines and CO2 to form calcium carbonate.

Claims

1. preparing a composition containing water, blast furnace slag, an amine compound, and an additive; agitating the composition to dissolve calcium from the blast furnace slag; and bringing atmospheric air into contact with the composition from which calcium has been eluted, thereby immobilizing carbon dioxide contained in the atmospheric air.

2. 2. The carbon dioxide fixation method according to claim 1, wherein the additive is at least one selected from hydrochloric acid, ethylenediaminetetraacetic acid, and cement.

3. 2. The carbon dioxide fixation method according to claim 1, wherein the amine compound is at least one selected from the group consisting of 2-amino-2-methyl-1-propanol, 2-(methylamino)ethanol, and N-methyldiethanolamine.

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