Production method for powder having reduced specific surface area and powder production device

Abstract

To provide: a production method for powder having reduced specific surface area which enables the powder having reduced specific surface area to be easily produced; and a powder production device.SOLUTION: A production method for powder having reduced specific surface area includes: a reaction step of supplying gas G containing carbon dioxide to a solution 3 containing a metal ion to react the metal ion and a carbonate ion to produce an intermediate 7; and a separation step of separating the intermediate 7 from the solution 3 to produce carbonate mineral powder 2 which is powdered. During the reaction step, a surfactant S for reducing specific surface area of the intermediate 7 is added to the solution 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for producing carbonate mineral powder with a reduced specific surface area. [Background technology]

[0002] Conventionally, for example, a method has been known in which concrete sludge generated in a concrete manufacturing process is added with water and stirred, and the dissolved calcium component is reacted with carbon dioxide to obtain calcium carbonate, which is then separated and dehydrated to produce a powder (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7257582 Summary of the Invention [Problem to be solved by the invention]

[0004] The powder produced as described above has a particle size of about 1 to 100 μm, irregular surface irregularities, and minute pores scattered all over the surface, so it has a very large specific surface area (BET specific surface area), ranging from 5 to 50 m. 2 Therefore, when this powder is used as an admixture for fresh concrete or as a filler for asphalt mixtures, many of the admixtures (medicinal-like), asphalt emulsions, and additives used in concrete blends adhere to the irregularities and pores on the powder surface, posing the problem of requiring a large amount to be used to achieve the required performance, resulting in high manufacturing costs.

[0005] The present invention has been made in consideration of the above points, and aims to provide a method and an apparatus for producing powder with a reduced specific surface area, which can easily produce powder with a reduced specific surface area. [Means for solving the problem]

[0006] The method for producing a powder with a reduced specific surface area of ​​the present invention comprises a reaction step in which a gas containing carbon dioxide is supplied to a solution containing metal ions to cause the metal ions to react with carbonate ions to produce an intermediate, and a separation step in which the intermediate is separated from the solution to produce a powder, i.e., a carbonate mineral powder, and during the reaction step, a surfactant is added to the solution to reduce the specific surface area of ​​the intermediate. [Effects of the Invention]

[0007] According to the present invention, it is possible to produce powder with a reduced specific surface area. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram schematically illustrating an example of a powder manufacturing apparatus according to an embodiment of the present invention. [Figure 2] 3 is a cross-sectional view schematically illustrating, in an enlarged scale, a portion of a carbonate mineral powder, which is a powder produced by a method for producing a powder with a reduced specific surface area using the powder production apparatus. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] In Fig. 1, reference numeral 1 denotes a powder manufacturing apparatus. The powder manufacturing apparatus 1 is a carbon dioxide fixation apparatus that uses a raw material to manufacture carbonate mineral powder 2 (hereinafter simply referred to as powder 2), which is a dry powder in which carbon dioxide is fixed.

[0011] The raw material contains a metal element that can react with carbon dioxide. The metal element is, for example, calcium (Ca) or magnesium (Mg), which reacts with carbonate ions to form a carbonate mineral. In this embodiment, calcium is used as an example.

[0012] The raw material may be, for example, concrete sludge or its solids generated after centrifugal molding during the production of secondary concrete products, or sludge from leftover concrete (remaining concrete) or returned concrete (returned concrete) at a ready-mix concrete plant, or quicklime made by crushing and burning mined limestone.

[0013] The raw material is used as a solution (saturated aqueous solution) 3 such as slurry-like concrete sludge water or milk of lime, in which metal ions, in this embodiment calcium ions, are eluted by adding water and stirring.

[0014] In this embodiment, the solution 3 is introduced into the reaction vessel 5 via a supply means 4. The supply means 4 has a pipe connected to a supply source of the solution 3, a valve for adjusting the supply amount, and the like.

[0015] The reaction vessel 5 is also called a vertical silo, for example, and is formed in a longitudinal shape in the vertical direction. A gas supply means 6 is arranged in the reaction vessel 5.

[0016] The gas supply means 6 is used to obtain an intermediate 7, which is a carbonate mineral in which carbon dioxide is immobilized, in this embodiment calcium carbonate (CaCO3), by bubbling gas G containing carbon dioxide through the solution 3 in the reaction vessel 5, thereby stirring the solution 3 with the bubbles and causing carbonate ions generated by ionization of carbon dioxide to react with calcium ions in the solution 3. The gas supply means 6 has piping, valves, nozzles, etc. connected to a gas supply source. The gas supply means 6 is connected to the bottom of the reaction vessel 5 and ejects gas G from the bottom of the reaction vessel 5 for a predetermined period of time. The ejection of gas G by the gas supply means 6 may be continuous or intermittent.

[0017] The gas G supplied by the gas supply means 6 is preferably exhaust gas from a gas supply source such as a boiler or a power plant.

[0018] In addition, in the reaction tank 5, a surfactant S is added to the solution 3 via an addition means 8. The addition means 8 includes, for example, a pipe connected to a supply source of the surfactant S and a valve for adjusting the supply amount.

[0019] As shown in FIG. 2, surfactant S is a coating agent for reducing the specific surface area (BET specific surface area) by forming a coating portion C that coats the fine irregularities and pores on the surface of intermediate 7. Any surfactant may be used as surfactant S, but fatty acid surfactants are preferably used, for example. As shown in FIG. 1, surfactant S is supplied in liquid form to solution 3, making it possible to uniformly form coating portion C (FIG. 2). In this embodiment, surfactant S is used in the form of a solution 100 times the original solution, i.e., a 1% solution.

[0020] Furthermore, dehydration means 9, which is a separation means, is connected to reaction tank 5. Dehydration means 9 directly obtains intermediate 7 that has precipitated in reaction tank 5, and dehydrates (drains) and dries this intermediate 7 to separate it from solution 3 and turn it into powder 2. Dehydration means 9 is connected to the bottom of reaction tank 5 so as to obtain intermediate 7 that has precipitated at the bottom of reaction tank 5.

[0021] Next, a method for producing the powder 2 (carbon dioxide fixation method) using the powder production apparatus 1 of this embodiment will be described.

[0022] First, a predetermined amount of solution 3, for example, 20 ml, is introduced into the reaction vessel 5 via the supply means 4. 3 (20,000 L) is introduced, and gas G containing carbon dioxide is supplied under pressure to the solution 3 at room temperature for a predetermined time, for example, 45 minutes, by gas supply means 6. As a result, calcium ions in the solution 3 react with carbonate ions generated by ionization of carbon dioxide, calcium carbonate is produced, and the carbon dioxide is fixed to the intermediate 7 (reaction step).

[0023] At this time, in the reaction vessel 5, after a predetermined time, for example, about 5 to 10 minutes, has elapsed since the start of gas supply from the gas supply means 6, intermediate 7 begins to form, and solution 3 becomes cloudy. Therefore, a predetermined amount of surfactant S, for example, 1 / 100 to 1 / 20 of the amount of solution 3, or 200 to 1000 L (2 to 10 L of stock solution) in this embodiment, is added to solution 3 via addition means 8. That is, surfactant S is added while gas G is being supplied to solution 3 from the gas supply means 6, and gas G continues to be supplied to solution 3 from the gas supply means 6 even after surfactant S is added. The added surfactant S coats the surface of the generated intermediate 7, reducing its specific surface area (BET specific surface area) and inhibiting aggregation of the intermediate 7, resulting in the production of minute intermediate 7.

[0024] Then, when the supply of gas from the gas supply means 6 is terminated, the intermediate 7 that has settled at the bottom of the reaction tank 5 is discharged from the reaction tank 5 to the dehydration means 9, where it is dehydrated, i.e., separated from the solution 3 and dried, to produce the powder 2 (separation step). The moisture content of the powder 2 produced through the dehydration means 9 may be set depending on the application of the powder 2.

[0025] The produced powder 2 is basically made of precipitated calcium carbonate, and is a granule having a particle size of about 1 to 100 μm, the surface of which is covered with a coating made of surfactant S.

[0026] In this way, during the reaction process in which a gas G containing carbon dioxide is supplied to a solution 3 containing metal ions to react the metal ions with carbonate ions to produce an intermediate 7, by adding a surfactant S to the solution 3 to reduce the specific surface area of ​​the intermediate 7, it becomes possible to easily produce a powder 2 whose specific surface area (BET specific surface area) has been reduced to, for example, 1 / 5 to 1 / 100.

[0027] The powder 2 thus produced can be used as, for example, an admixture for fresh concrete or concrete mixing, or as a filler for asphalt compounds, which not only facilitates mixing operations, but also reduces the amount of additives such as admixtures and asphalt emulsions that need to be added, thereby lowering the unit price of the product, and also makes it possible to utilize the fixed matter that fixes carbon dioxide. [Explanation of symbols]

[0028] 1 Powder manufacturing equipment 2. Carbonate mineral powder 3 solution 5. Reaction tank 6 Gas supply means 7 Intermediates 8 Means of addition 9. Dehydration means as a means of separation G Gas S surfactant

Claims

1. a reaction step of supplying a gas containing carbon dioxide to a solution containing metal ions to react the metal ions with carbonate ions to produce an intermediate; a separation step of separating the intermediate from the solution to produce a powder of carbonate mineral, During the reaction step, a surfactant is added to the solution to reduce the specific surface area of ​​the intermediate. A method for producing a powder having a reduced specific surface area, comprising:

2. The powder is an admixture for fresh concrete or a filler material for asphalt mixtures, The metal ion is a calcium ion.

2. The method for producing powder with a reduced specific surface area according to claim 1.

3. a reaction vessel into which a solution containing metal ions is introduced; a gas supply means for supplying a gas containing carbon dioxide to the solution introduced into the reaction vessel; an adding means for adding a surfactant to the solution to reduce the specific surface area of ​​an intermediate produced by the reaction between the metal ions and the carbonate ions while the gas is being supplied to the solution by the gas supplying means; a separation means for separating the intermediate from the solution to produce a powder of carbonate mineral; A powder manufacturing apparatus comprising:

4. The powder is an admixture for fresh concrete or a filler material for asphalt mixtures, The metal ion is a calcium ion.

4. The powder manufacturing apparatus according to claim 3.

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