Process for producing carbonates or bicarbonates of alkali metals

Abstract

A method for producing a carbonate or bicarbonate of an alkali metal, comprising: supplying a gas bubble containing carbon dioxide, i.e., a carbon dioxide-containing gas bubble, to an aqueous solution (a) of at least one alkali metal compound selected from the group consisting of an alkali metal hydroxide, an alkali metal carbonate, and an alkali metal chloride, wherein, in the case where the aqueous solution (a) is an aqueous solution of an alkali metal chloride, the carbon dioxide-containing gas bubble is supplied after ammonia is supplied to the aqueous solution (a), the carbon dioxide-containing gas bubble having a size of d50 of 100 μm or less and d90 of 150 μm or less.

Description

Technical Field

[0001] This invention relates to a method for manufacturing alkali metal carbonates or bicarbonates.

[0002] This invention claims priority based on Japanese Patent Application No. 2024-040341 ​​filed in Japan on March 14, 2024, the contents of which are incorporated herein by reference. Background Technology

[0003] Alkali metal bicarbonates, such as sodium bicarbonate, are produced by crystallization from aqueous solutions. For example, the so-called ammonia-soda process, in which sodium bicarbonate crystals are obtained by sequentially blowing ammonia and carbon dioxide into an aqueous solution containing sodium ions, has been known since ancient times.

[0004] In addition, as a method for obtaining alkali metal carbonates and / or bicarbonates, there are known methods for carbonation and hydrocarbonation by supplying a gas containing carbon dioxide to an aqueous solution of an alkali metal hydroxide or alkali metal carbonate. For example, there is a method for continuously supplying an aqueous solution of sodium carbonate and a gas containing carbon dioxide to a tank in which sodium bicarbonate is suspended, and causing them to react to precipitate sodium bicarbonate.

[0005] Patent document 1 discloses a method for manufacturing sodium bicarbonate, in which an aqueous solution of sodium hydroxide or an aqueous solution of sodium carbonate is reacted with carbon dioxide to obtain a sodium bicarbonate solution, and the solution is cooled to precipitate sodium bicarbonate crystals.

[0006] Patent document 2 discloses the following method: after pre-combining an aqueous solution of sodium hydroxide with a gas containing carbon dioxide, the solution is supplied to a storage tank containing an alkaline aqueous solution to precipitate sodium bicarbonate.

[0007] On the other hand, Patent Document 3 discloses a device for efficiently recovering carbon dioxide, which supplies carbon dioxide to a reaction tank containing an aqueous solution of alkali metal hydroxide via a perforated plate, thereby supplying carbon dioxide in a manner that requires no electricity.

[0008] Patent document 4 discloses the following method: In the sodium carbonate aqueous solution produced in the caprolactam production process, a microbubbler, which is a high-pressure nozzle type disperser, is used to supply combustion exhaust gas containing carbon dioxide, thereby producing sodium bicarbonate slurry.

[0009] Patent document 5 discloses a method for producing sodium bicarbonate by reacting an aqueous sodium carbonate solution with carbon dioxide, wherein carbon dioxide is supplied in the form of microbubbles with an average diameter of less than 0.1 mm using a rotary collision mixer.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 3-275509

[0013] Patent Document 2: Japanese Patent Application Publication No. 2012-206872

[0014] Patent Document 3: Japanese Patent Application Publication No. 2023-65903

[0015] Patent Document 4: Korean Patent No. 10-2205282

[0016] Patent Document 5: Korean Patent No. 10-2313559 Summary of the Invention

[0017] The problem the invention aims to solve

[0018] The production of carbonates and bicarbonates is carried out by contacting an aqueous solution of an alkali metal hydroxide or an aqueous solution of an alkali metal carbonate with a gas containing carbon dioxide, thereby dissolving carbon dioxide in the aqueous solution. Therefore, the inventors believe that micronizing carbon dioxide to accelerate the dissolution rate is closely related to improving the utilization rate of carbon dioxide and accelerating the formation rate of carbonates and bicarbonates.

[0019] However, Patent Documents 1 and 2 did not consider this point, but simply supplied gas containing carbon dioxide through a pipe. Therefore, only a portion of the supplied carbon dioxide reacted with alkali metal hydroxides or alkali metal carbonates, resulting in low utilization of carbon dioxide. Depending on the circumstances, equipment for recovering unreacted carbon dioxide may also be required.

[0020] In Patent Document 3, although the absorption rate of carbon dioxide is improved by supplying it through a perforated plate, it cannot be considered sufficient. Furthermore, the perforated plate may become clogged if bicarbonate precipitates.

[0021] In Patent Document 4, although a device called a microbubbler was used to supply carbon dioxide, the conversion rate of carbon dioxide only reached about 60%. The reason is believed to be that the carbon dioxide was not sufficiently atomized in the sodium carbonate aqueous solution.

[0022] In Patent Document 5, a reactor consisting of a bubble reactor and an adsorption tower maintained at a pressure of 4 bar was used to supply pressurized carbon dioxide as microbubbles, but the utilization rate of carbon dioxide was only about 90%. It is believed that the reason is still due to insufficient micronization of carbon dioxide bubbles.

[0023] The present invention was made in view of the above circumstances, and its object is to provide a manufacturing method that, in the manufacture of alkali metal carbonates or bicarbonates, can perform reactions such as carbonation of alkali metal hydroxides and hydrocarbonation of alkali metal carbonates at high speed, and can achieve effective utilization of gases with low carbon dioxide concentrations and improve the utilization rate of carbon dioxide.

[0024] Solution for solving the problem

[0025] The inventors conducted in-depth research and found that the above-mentioned problem could be solved by supplying sufficiently micronized carbon dioxide-containing bubbles to an aqueous solution (a) of at least one alkali metal compound selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal chlorides, thereby completing the present invention.

[0026] The present invention includes the following described methods.

[0027] [1] A method for manufacturing an alkali metal carbonate or bicarbonate, comprising: supplying a gas bubble containing carbon dioxide, i.e. a carbon dioxide-containing bubble, to an aqueous solution (a) of at least one alkali metal compound selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal chlorides.

[0028] In the case where the aqueous solution (a) is an aqueous solution of an alkali metal chloride, carbon dioxide-containing bubbles are supplied after ammonia is supplied to the aqueous solution (a).

[0029] The size of the carbon dioxide-containing bubbles is less than 100 μm in d50 and less than 150 μm in d90.

[0030] [2] The method for manufacturing alkali metal carbonates or bicarbonates according to [1], wherein the alkali metal carbonates or bicarbonates are lithium carbonate, sodium carbonate, potassium carbonate, lithium bicarbonate, sodium bicarbonate or potassium bicarbonate.

[0031] [3] The method for manufacturing alkali metal carbonates or bicarbonates according to [1] or [2], wherein the concentration of carbon dioxide in the gas containing carbon dioxide is 10% by volume or more.

[0032] [4] The method for manufacturing alkali metal carbonates or bicarbonates according to any one of [1] to [3], wherein the size of the carbon dioxide-containing bubbles is d50 of 50 to 90 μm and d90 of 100 to 150 μm.

[0033] [5] A method for manufacturing an alkali metal bicarbonate, wherein,

[0034] The slurry containing alkali metal bicarbonate obtained by the manufacturing method of any one of [1] to [4] was filtered.

[0035] Add a first aqueous solution (a) of at least one alkali metal compound selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal chlorides to the obtained filtrate to obtain a second aqueous solution (a).

[0036] Carbon dioxide-containing bubbles are supplied to the second aqueous solution (a) to obtain a third aqueous solution (a) of an alkali metal carbonate or bicarbonate.

[0037] The solution is concentrated by removing water from the obtained third aqueous solution (a) to obtain the fourth aqueous solution (a).

[0038] Carbon dioxide-containing bubbles are supplied to the resulting fourth aqueous solution (a), thereby causing the alkali metal bicarbonate to precipitate.

[0039] [6] A method for manufacturing an alkali metal bicarbonate powder, wherein an aqueous solution or slurry containing an alkali metal bicarbonate is obtained by any one of [1] to [5].

[0040] The obtained aqueous solution or slurry is subjected to dehydration and drying treatment to obtain powder of alkali metal bicarbonate.

[0041] [7] A method for manufacturing powder of an alkali metal bicarbonate, wherein the average particle size (d50) of the powder of the alkali metal bicarbonate is less than 100 μm.

[0042] The effects of the invention

[0043] According to the present invention, a manufacturing method is provided that, in the production of alkali metal carbonates or bicarbonates, can perform reactions such as carbonation of alkali metal hydroxides and hydrocarbonation of alkali metal carbonates at high speed, and can achieve effective utilization of gases with low carbon dioxide concentrations and improve the utilization rate of carbon dioxide. Attached Figure Description

[0044] Figure 1 This is a flowchart illustrating an example of the manufacturing method of the present invention.

[0045] Figure 2 This is a flowchart illustrating another example of the manufacturing method of the present invention. Detailed Implementation

[0046] The meanings of the terms used in this specification are as follows.

[0047] The range of values ​​represented by "~" refers to the range of values ​​with the values ​​before and after "~" as the lower and upper limits, respectively.

[0048] “d10”, “d50” and “d90” refer to the 10% diameter, 50% diameter (median diameter) and 90% diameter in the cumulative distribution curve of the volume of the bubble (or particle) relative to the size of the bubble (or particle), respectively.

[0049] "Carbon dioxide utilization rate" refers to the percentage ratio (B) of the amount of carbon dioxide gas required to completely convert the alkali metal compound in the aqueous solution (a) into the alkali metal carbonate or bicarbonate, relative to the amount of carbon dioxide gas supplied (A) for the production of alkali metal carbonates or bicarbonates.

[0050] The present invention will now be described, but the present invention is not limited to the examples in the following description.

[0051] The method for manufacturing alkali metal carbonates or bicarbonates according to this embodiment includes supplying bubbles containing carbon dioxide gas, i.e., carbon dioxide-containing bubbles, to an aqueous solution (a) of at least one alkali metal compound selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal chlorides. Wherein, if the aqueous solution (a) is an aqueous solution of an alkali metal chloride, the carbon dioxide-containing bubbles are supplied after ammonia is supplied to the aqueous solution (a).

[0052] Aqueous Solution (a)

[0053] The aqueous solution (a) is an aqueous solution of at least one alkali metal compound selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal chlorides.

[0054] The upper limit of the concentration of alkali metal compounds in aqueous solution (a) is the saturation concentration of alkali metal compounds.

[0055] The concentration of the alkali metal compound in the aqueous solution (a) is preferably 3% or more, more preferably 5% or more.

[0056] The lower limit of the concentration of the alkali metal compound in the aqueous solution (a) is preferably the concentration that exceeds the solubility of sodium bicarbonate at 0°C when the alkali metal compound reacts with carbon dioxide to form sodium bicarbonate.

[0057] In particular, the concentration of sodium carbonate in the aqueous solution (a) is preferably 6-25%, more preferably 10-20%. If it is above the lower limit, when sodium bicarbonate is generated by reacting with carbon dioxide, the amount tends to exceed the solubility of sodium bicarbonate, and sodium bicarbonate tends to precipitate. On the other hand, if it is below the upper limit, the amount of sodium bicarbonate in the slurry containing the generated sodium bicarbonate is appropriate, the viscosity of the slurry does not become too high, and it is easy to handle.

[0058] Alkali metals

[0059] Examples of alkali metals include lithium, sodium, and potassium. When using these alkali metals, the target product of the method of this embodiment can be carbonates or bicarbonates such as lithium carbonate, lithium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

[0060] Bubbles containing carbon dioxide

[0061] Bubbles containing carbon dioxide are bubbles containing gas containing carbon dioxide.

[0062] For gases containing carbon dioxide, there are no particular limitations as long as the concentration of carbon dioxide is 10% by volume or more. This includes, but is not limited to, exhaust gases from combustion furnaces, exhaust gases from glass melting furnaces, gases produced by neutralization of carbonates, or mixtures of carbon dioxide with air and nitrogen. High-purity carbon dioxide gas can also be used. The preferred range for carbon dioxide concentration is 30% by volume or more, and more preferably 50% by volume or more. There is no particular upper limit to the carbon dioxide concentration; it can be 100% by volume.

[0063] In the manufacturing method of this embodiment, tiny bubbles containing carbon dioxide gas are formed, and these bubbles are supplied to the aqueous solution of the alkali metal compound (a).

[0064] The carbon dioxide-containing bubbles described above have a d50 of less than 100 μm and a d90 of less than 150 μm. These carbon dioxide-containing bubbles can be obtained by appropriately adjusting the conditions of known microbubble preparation methods.

[0065] Microbubbles refer to a general term encompassing micron-sized bubbles with a diameter of 1–100 μm and nanobubbles with a diameter of less than 1 μm. If a large number of micron-sized bubbles are generated in water, turbidity will occur. On the other hand, because nanobubbles are extremely small, the water remains transparent. By microbubbling a gas containing carbon dioxide, the dissolution rate of carbon dioxide can be accelerated, and almost all of the supplied carbon dioxide can react with the alkali metal compound, thus enabling the carbon dioxide to react without loss. Therefore, not only is there no need for conventional unreacted carbon dioxide recovery equipment, but even gases with low carbon dioxide concentrations can react at a sufficient rate. Furthermore, as a reaction apparatus, it has the advantage of being a simple device that can operate at atmospheric pressure, eliminating the need to design the tank containing the aqueous solution (a) of the aforementioned alkali metal compound under pressure.

[0066] There are no particular limitations on the apparatus used to produce such microbubbles; the following apparatus can be cited as examples.

[0067] The device in Example 1 supplies gas to the suction side of a pressure pump, causing the gas drawn in by mixing blades rotating at high speed within the pressure pump to be microbubbled. As a specific example, the "vortex turbine mixing pump" (trade name) manufactured by Nikuni Co., Ltd. can be cited.

[0068] The apparatus in Example 2 is based on the Venturi effect (which narrows the flow path of a pressurized liquid to increase the flow velocity and thus create a low-pressure section). A low-pressure section is formed in the liquid flow, and gas is supplied to this section to create microbubbles. Specific examples include the "YJ nozzle" (trade name) manufactured by ENVIRO·VISION CO., LTD and the "Aqua-Transfer nozzle" (trade name) manufactured by Water Navi Corporation.

[0069] The apparatus in Example 3: Water is sprayed radially from a high-speed rotating disc, creating a negative pressure zone in the center that attracts gas and atomizes it into microbubbles. As a specific example, "SPINOR" (trade name) manufactured by Water Navi Corporation can be cited.

[0070] The size of carbon dioxide-containing bubbles can be determined, for example, by focused beam reflectance measurement. As the apparatus used in focused beam reflectance measurement, a particle size analyzer based on FBRM (Focused Beam Reflectance Measurement) manufactured by Mettler Toledo Corporation (trade name: Particle Track) can be used. In this specification, the size distribution of carbon dioxide-containing bubbles is represented by the 10% diameter (d10), 50% diameter (median diameter, d50), and 90% diameter (d90) in the cumulative distribution curve of bubble volume relative to bubble size.

[0071] In this embodiment, by using carbon dioxide-containing bubbles with a d50 of 100 μm or less and a d90 of 150 μm or less, the utilization rate of carbon dioxide can be significantly improved in the reactions of carbonation of alkali metal hydroxides and hydrocarbonation of alkali metal carbonates or alkali metal chlorides.

[0072] It should be noted that, from the viewpoint of making the effects of the present invention more reliable, d50 is preferably 50~90μm, more preferably 60~80μm, and d90 is preferably 100~150μm, more preferably 100~130μm.

[0073] It should be noted that, in this invention, so-called microbubbles with a diameter of less than 1 μm may not be present. There is no particular limitation on the minimum diameter of the carbon dioxide-containing bubbles, but from the viewpoint of ease of adjustment of the carbon dioxide-containing bubbles, a diameter greater than 1 μm or greater than 10 μm is preferred. According to the method of this invention, even without microbubbles with a diameter of less than 1 μm, the utilization rate of carbon dioxide can be sufficiently improved.

[0074] Supplying carbon dioxide-containing bubbles to aqueous solution (a)

[0075] When the alkali metal compound is an alkali metal hydroxide, the temperature of the aqueous solution (a) used to supply the carbon dioxide-containing bubbles is not particularly limited, but is preferably 0°C to 80°C. The lower the temperature, the greater the solubility of carbon dioxide in the aqueous solution (a) of the alkali metal hydroxide; however, if the temperature is above 0°C, there is no concern about freezing, which is therefore preferable. On the other hand, the higher the temperature, the lower the solubility of carbon dioxide in the aqueous solution (a) of the alkali metal hydroxide; therefore, if the temperature is below 80°C, the formation rate of the alkali metal carbonate is less likely to slow down, which is also preferable. The temperature of the aqueous solution (a) is more preferably 20°C to 60°C, and even more preferably 30°C to 50°C.

[0076] When the alkali metal compound is an alkali metal carbonate, the temperature of the aqueous solution (a) used to supply the carbon dioxide-containing bubbles is not particularly limited, but is preferably 0°C to 80°C. The lower the temperature, the greater the solubility of carbon dioxide in the aqueous solution of the alkali metal carbonate; however, if the temperature is above 0°C, there is no concern about freezing, which is therefore preferable. On the other hand, the higher the temperature, the lower the solubility of carbon dioxide in the aqueous solution (a) of the alkali metal carbonate; therefore, if the temperature is below 80°C, the formation rate of the alkali metal carbonate is less likely to slow down, which is also preferable. Furthermore, the higher the temperature, the higher the solubility of the formed alkali metal bicarbonate; however, if the temperature is below 80°C, the amount of precipitated alkali metal bicarbonate increases, which is also preferable. The temperature of the aqueous solution (a) is more preferably 20°C to 70°C, and even more preferably 25°C to 50°C.

[0077] There are no particular restrictions on the time for supplying carbon dioxide-containing bubbles to the aqueous solution (a), as long as the desired reaction can be carried out sufficiently. It is usually 0.2 to 16 hours, preferably 0.5 to 8 hours.

[0078] When the alkali metal compound is an alkali metal chloride such as sodium chloride, carbon dioxide-containing bubbles are supplied after ammonia is supplied to the aqueous solution (a). In this case, the steps and conditions other than the use of carbon dioxide-containing bubbles can be carried out according to the well-known ammonia-soda process.

[0079] The following describes a specific embodiment of the method of the present invention.

[0080] Carbon dioxide-containing bubbles are supplied to an aqueous solution (a) of alkali metal carbonate (first aqueous solution (a)) to obtain a slurry in which alkali metal bicarbonate has precipitated. The slurry is then filtered, and an aqueous solution of alkali metal hydroxide (first aqueous solution (a)) is added to the resulting filtrate (b) to obtain a second aqueous solution (a). Carbon dioxide-containing bubbles are supplied to this second aqueous solution (a) to form an aqueous solution of alkali metal carbonate, and the solution is then concentrated by removing water to obtain a third aqueous solution (a). Carbon dioxide-containing bubbles are then supplied again to this concentrated aqueous solution of alkali metal carbonate (third aqueous solution (a)) to precipitate alkali metal bicarbonate.

[0081] The filtrate (b) obtained by filtering the slurry from which alkali metal bicarbonates have precipitated is a saturated aqueous solution of alkali metal bicarbonates. Therefore, by setting up such a process, in this invention, the saturated aqueous solution of the alkali metal bicarbonates can be reused as a raw material for alkali metal bicarbonates, thus avoiding the loss of alkali metal and carbon dioxide used as raw materials, and enabling the complete recovery of alkali metal bicarbonates.

[0082] The reason for concentrating the aqueous solution of alkali metal carbonates by removing water, as described above, is that with repeated cycles of this process, the slurry containing alkali metal bicarbonates gradually increases in volume, requiring a large tank to hold it. For example, when the alkali metals are sodium or potassium, only a maximum concentration of 48% sodium hydroxide or potassium hydroxide aqueous solution can be obtained. If water is not removed, the volume of the slurry containing sodium bicarbonate or potassium bicarbonate will gradually increase. If the concentration of the aqueous solution of alkali metal hydroxide can reach 66%, then water removal is unnecessary.

[0083] As a method for concentrating water by removing moisture from the aqueous solution of the aforementioned alkali metal carbonates, there are no particular limitations. The method of supplying the aqueous solution with fine bubbles of gas with low water vapor partial pressure is preferred because it removes moisture with minimal equipment. As an apparatus for forming the fine bubbles, the same apparatus as described above can be used. It is sufficient to have a pump and piping for circulating the aqueous solution and piping for the gas.

[0084] Another method is the use of a so-called packed tower. This method involves using a packed tower filled with materials such as Pall rings to spray the aqueous solution from above while simultaneously supplying a gas with low water vapor partial pressure from below, thus achieving gas-liquid contact. However, this method requires a packed tower in addition to the pump and piping for circulating the aqueous solution and the piping for the gas.

[0085] Furthermore, methods can be exemplified by heating an aqueous solution to evaporate the water. Examples of heating methods include: designing the container containing the aqueous solution as a structure with an outer jacket, or immersing a coil in the aqueous solution and introducing steam or hot water at atmospheric pressure or higher into the jacket or coil. However, in this method, in addition to the pump and piping for circulating the aqueous solution and the piping for the gas, equipment is also required to generate steam or hot water and supply them to the container containing the aqueous solution.

[0086] The following is for reference Figure 1 The first embodiment of the method of the present invention will be described, but this is only one example of the embodiment of the present invention, and the present invention is not limited to this example.

[0087] Figure 1 This is a flowchart illustrating an example of the manufacturing method of the present invention, and an example of the overall configuration of a sodium bicarbonate manufacturing apparatus for carrying out the method of the present invention.

[0088] exist Figure 1 In this process, the sodium carbonate aqueous solution concentration adjustment tank 1 is an atmospheric pressure tank equipped with a stirring device 2. Additionally, the sodium carbonate aqueous solution 3 is contained within the concentration adjustment tank 1. The sodium carbonate aqueous solution 3 is adjusted to a specified concentration using a method described later. This sodium carbonate aqueous solution 3, adjusted to the specified concentration, is supplied to the sodium bicarbonate precipitation tank 6 via a delivery pipe 5 using a vortex turbine mixing pump 4. The sodium bicarbonate precipitation tank 6 is an atmospheric pressure tank equipped with a stirring device 7. The liquid 8 in the sodium bicarbonate precipitation tank is initially a sodium carbonate aqueous solution with adjusted concentration, but it is circulated in the sodium bicarbonate precipitation tank 6 via a circulation pipe 10 using a vortex turbine mixing pump 9. Furthermore, carbon dioxide-containing gas is introduced into the suction side of the vortex turbine mixing pump 9 through a carbon dioxide-containing gas supply pipe 11, where d50 and d90 are within the aforementioned ranges, after being microbubbled. As the carbon dioxide-containing gas is introduced, the pH of the liquid 8 in the sodium bicarbonate precipitation tank decreases, causing sodium bicarbonate to precipitate and the liquid to become cloudy. When the pH of the liquid 8 in the sodium bicarbonate precipitation tank finally reaches below 8.5, the supply of gas containing carbon dioxide is stopped, and sodium bicarbonate slurry is obtained.

[0089] The sodium bicarbonate slurry is extracted using a vortex turbine mixing pump 9 via a delivery pipe 12. The extracted slurry is then filtered through a centrifugal dewatering machine 13. The filter cake obtained from centrifugal dewatering is transported to a drying device 15 via a delivery pipe 14, where it is dried to obtain sodium bicarbonate powder 16. During this centrifugal dewatering process, filtrate 17 is also produced. This filtrate 17 is saturated sodium bicarbonate water, which, after being recovered to a filtrate recovery tank 18, is returned to the sodium carbonate aqueous solution concentration adjustment tank 1 via a filtrate delivery pump 19 and a filtrate delivery pipe 20.

[0090] In the sodium carbonate aqueous solution concentration adjustment tank 1, sodium hydroxide is added to the filtrate 17 through the sodium hydroxide addition pipe 21. With the addition of sodium hydroxide, the pH of the aqueous solution becomes approximately 14. Then, using a vortex turbine mixing pump 4, the sodium hydroxide-added aqueous solution is circulated in the sodium carbonate aqueous solution concentration adjustment tank 1 through the circulation pipe 22. Carbon dioxide is then introduced into the suction side of the vortex turbine mixing pump 4 through the carbon dioxide gas supply pipe 23, where d50 and d90 are within the aforementioned range, after being microbubbled. As carbon dioxide gas is introduced, the pH of the liquid 8 in the sodium carbonate aqueous solution concentration adjustment tank 1 decreases, eventually reaching the pH of the sodium carbonate aqueous solution (approximately 12). At this point, the supply of carbon dioxide gas is stopped, resulting in a sodium carbonate aqueous solution. Next, the sodium carbonate aqueous solution is circulated in the sodium carbonate aqueous solution concentration adjustment tank 1 using the vortex turbine mixing pump 4 through the circulation pipe 22. Air is then microbubbled and introduced into the suction side of the vortex turbine mixing pump 4 through the air supply pipe 24. As air is introduced, the water in the sodium carbonate aqueous solution evaporates and is concentrated, adjusted to the specified sodium carbonate concentration.

[0091] Next, refer to Figure 2 The second embodiment of the method of the present invention will be described, but this is only one example of the embodiment of the present invention, and the present invention is not limited to this example.

[0092] Figure 2 This is a flowchart illustrating another example of the manufacturing method of the present invention, and an example of the overall configuration of a sodium bicarbonate manufacturing apparatus for carrying out the method of the present invention.

[0093] In the second embodiment, as a change from the first embodiment, a YJ nozzle is used instead of a vortex turbine mixing pump as an apparatus for generating microbubbles containing carbon dioxide gas.

[0094] exist Figure 2 In this process, a magnetic pump 25 supplies liquid from the sodium carbonate aqueous solution concentration adjustment tank 1 to the YJ nozzle 27. Gas containing carbon dioxide is supplied to the center of the YJ nozzle 27 via a supply pipe 23, causing it to be microbubbled within the YJ nozzle with d50 and d90 within the aforementioned range. Thus, a sodium carbonate aqueous solution 3 is obtained in the sodium carbonate aqueous solution concentration adjustment tank 1.

[0095] Similarly, the liquid in the sodium bicarbonate precipitation tank 6 is supplied to the YJ nozzle 28 using a magnetic pump 26. Gas containing carbon dioxide is supplied to the center of the YJ nozzle 28 via a supply pipe 11, causing it to be microbubbled within the nozzle at a range of d50 and d90. As a result, sodium bicarbonate precipitates in the sodium bicarbonate precipitation tank 6, yielding a sodium bicarbonate slurry.

[0096] The method for manufacturing alkali metal carbonates or bicarbonates according to the present invention can improve the utilization rate of carbon dioxide. Here, the utilization rate of carbon dioxide is preferably 95% or more, more preferably 98% or more, and most preferably 100%.

[0097] The above describes the method for manufacturing alkali metal carbonates or bicarbonates according to the present invention. However, the present invention is not limited to the composition described in the above embodiments, and its composition may be appropriately modified without departing from its spirit.

[0098] Furthermore, according to this manufacturing method, the hydrocarbonation reaction of alkali metal carbonates can be carried out at high speed to obtain small alkali metal bicarbonates (e.g., sodium bicarbonate) with an average particle size of less than 100 μm. Therefore, this manufacturing method also has the effect of easily producing micronized alkali metal bicarbonate powders with an average particle size of 8 to 15 μm (approximately 10 μm). These micronized powders have characteristics such as a large specific surface area, making them suitable for treating waste gases generated in thermal power plants, waste incineration facilities, biomass power plants, etc., i.e., for removing acidic gases contained in the waste gases.

[0099] It should be noted that the "average particle size" here refers to the cumulative 50% diameter based on volume (= median diameter, d50). Small alkali metal bicarbonates are preferably 100 μm or less, more preferably 50 μm or less, more preferably 35 μm or less, further preferably 25 μm or less, particularly preferably 20 μm or less, and most preferably 10 μm or less.

[0100] That is, in one aspect of the present invention, a method for manufacturing powder of alkali metal bicarbonate is provided, wherein an aqueous solution or slurry containing alkali metal bicarbonate is obtained by the above manufacturing method, and the obtained aqueous solution or slurry is subjected to dehydration treatment and drying treatment to obtain powder of alkali metal bicarbonate.

[0101] Here, the dehydration and drying processes can be carried out by known methods, for example, under conditions where the moisture content of the obtained powder is 1.0% by mass or less or 0.1% by mass or less. The aforementioned moisture content can be determined using known methods, such as the method described in Japanese Patent Application Publication No. 2003-83947.

[0102] Example

[0103] The present invention will now be described in detail through embodiments, but the present invention is not limited to these embodiments. It should be noted that, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass," respectively.

[0104] Examples 1-5 and 9 are examples, and examples 6-8 and 10 are comparative examples.

[0105] "Determination Methods and Evaluation Methods"

[0106] (Size of bubbles containing carbon dioxide)

[0107] The size of carbon dioxide-containing bubbles was determined using a particle size analyzer based on FBRM (Focused Beam Reflectance Measurement) manufactured by Mettler Toledo, Inc. (trade name: Particle Track G400). Specifically, in Figure 1 or Figure 2 In this process, the measuring probe is immersed in either a sodium carbonate aqueous solution 3 or a sodium bicarbonate precipitation tank liquid 8 to measure the size of the bubbles. The distribution of bubble size is represented by the 10% diameter (d10), 50% diameter (median diameter, d50), and 90% diameter (d90) in the cumulative distribution curve of bubble volume relative to bubble size.

[0108] (Carbon dioxide utilization rate)

[0109] The ratio (B) of the calculated amount of carbon dioxide gas required to completely convert sodium carbonate in the sodium carbonate aqueous solution into sodium bicarbonate, expressed as a percentage, to the actual amount of carbon dioxide gas supplied for the precipitation of sodium bicarbonate (A) is defined as the carbon dioxide utilization rate (UR1) (%) during the precipitation of sodium bicarbonate. That is, the carbon dioxide utilization rate (UR1) can be obtained by the following formula (1).

[0110] The utilization rate of carbon dioxide during sodium bicarbonate precipitation (UR1) (%) = Calculated amount of carbon dioxide gas required to completely convert sodium carbonate into sodium bicarbonate (B, unit: L) / Actual amount of carbon dioxide gas supplied (A, unit: L) × 100 Equation (1)

[0111] Furthermore, the ratio (D) of the calculated amount of carbon dioxide required to convert the filtrate obtained by centrifugation and the sodium hydroxide mixture into an aqueous sodium carbonate solution to the amount of carbon dioxide supplied (C) is defined as the carbon dioxide utilization rate (UR2) (%) during the preparation of the aqueous sodium carbonate solution. That is, the carbon dioxide utilization rate (UR2) can be obtained by the following formula (2).

[0112] The utilization rate of carbon dioxide in the preparation of sodium carbonate aqueous solution (UR2) (%) = Calculated amount of carbon dioxide gas required to convert the mixture of filtrate and sodium hydroxide into sodium carbonate aqueous solution (D, unit: L) / Actual amount of carbon dioxide gas supplied (C, unit: L) × 100 Equation (2)

[0113] (Average particle size d50 of sodium bicarbonate)

[0114] The particle size distribution of sodium bicarbonate particles dispersed in a mixed solvent (methanol = 11%, ethanol = 88%, isopropanol = 1%) was measured using a Microtrac FRA particle size distribution measuring device manufactured by Nikkiso Corporation, and the cumulative 50% diameter (median diameter, d50) on a volume basis was determined.

[0115] (Example 1)

[0116] use Figure 1 The apparatus of the first embodiment is shown. First, 800g of sodium carbonate powder and 4000g of ion-exchanged water are added to a concentration adjustment tank 1 with an internal volume of 8L for sodium carbonate aqueous solution and stirred to obtain 4800g of sodium carbonate aqueous solution with a concentration of 16.7%. Next, this aqueous solution is transferred to a sodium bicarbonate precipitation tank 6 with an internal volume of 8L, and a vortex turbine mixing pump 9 is started, and circulation is performed using a circulation piping 10. The vortex turbine mixing pump 9 is a KTM15ND02S type manufactured by Nikuni Co., Ltd. The circulation flow rate is 20L / min. After the circulation starts, carbon dioxide gas (carbon dioxide concentration 100% by volume) is supplied to the suction piping side of the vortex turbine mixing pump 9 at a rate of 1.0L / min, and the carbon dioxide is introduced after being microbubbled. The size of the carbon dioxide bubbles is d50=63μm and d90=107μm. The temperature of the aqueous solution when introducing carbon dioxide is 25~35°C. 169 minutes after the start of the carbon dioxide-containing bubble supply, the sodium bicarbonate precipitation tank 6 became a cloudy sodium bicarbonate slurry with a pH of 8.0. The carbon dioxide utilization rate (UR1) was 100%.

[0117] The sodium bicarbonate slurry was filtered using a centrifugal dewatering machine 13 to obtain 1117 g of centrifugal dewatered filter cake and 4015 g of filtrate. The centrifugal dewatering machine 13 was a KOKUSAN Co.Ltd. H-110F model. The centrifugal dewatered filter cake was dried under a carbon dioxide atmosphere at 80°C to obtain 893 g of sodium bicarbonate powder. The average particle size d50 of the obtained sodium bicarbonate powder was 31 μm. Using a pulverizer (manufactured by Enwaile Corporation, SP-3 model), 200 g of the obtained sodium bicarbonate powder was pulverized for 30 minutes at a blade rotation speed of 4,000 rpm to obtain a micro powder with an average particle size d50 of 11 μm.

[0118] On the other hand, the filtrate, saturated sodium bicarbonate solution (concentration 9.3%), was returned to the sodium carbonate aqueous solution concentration adjustment tank 1. After adding 886g of 48% sodium hydroxide aqueous solution, the vortex turbine mixing pump 4 was started, and circulation was performed using the circulation piping 22. The circulation flow rate was 20L / min. A Nikuni Co., Ltd. KTM15ND02S type vortex turbine mixing pump was used. After initial circulation, carbon dioxide gas was supplied to the suction piping side of the vortex turbine mixing pump 4 at a rate of 1.0L / min, and the carbon dioxide was microbubbled before being introduced. The carbon dioxide bubble size was d50=63μm, d90=106μm. After 69 minutes, the liquid in the sodium carbonate aqueous solution concentration adjustment tank 1 became a sodium carbonate aqueous solution with pH=12.0, weight=5037g, and sodium carbonate content=800g. The carbon dioxide utilization rate (UR2)=100%.

[0119] Next, the vortex turbine mixing pump 4 is started, and the circulation flow rate is maintained at 20 L / min using the circulation piping 22. Air is supplied to the suction side of the vortex turbine mixing pump 4 at a rate of 1.0 L / min, and the air is introduced after being microbubbled. The sodium carbonate aqueous solution in the concentration adjustment tank 1 is gradually concentrated through the evaporation of water. After 9 hours, the weight of the sodium carbonate aqueous solution is 4800 g. The sodium carbonate content is 800 g, which is the same as the content of the initially prepared sodium carbonate aqueous solution.

[0120] The various conditions and results are shown in Tables 1 and 2.

[0121] (Example 2)

[0122] In the sodium bicarbonate precipitation tank 6, the gas added to the suction pipe side of the vortex turbine mixing pump 9 was changed to a mixture of 0.3 L / min carbon dioxide and 0.7 L / min air, and supplied through microbubbling. Otherwise, the process was the same as in Example 1. The size of the bubbles in the carbon dioxide-containing gas mixture was d50 = 75 μm and d90 = 143 μm. The temperature of the aqueous solution when introducing carbon dioxide was 25–35 °C. 563 minutes after the start of supplying the carbon dioxide-containing bubbles, the sodium bicarbonate precipitation tank contained a turbid sodium bicarbonate slurry with pH = 8.0. The carbon dioxide utilization rate (UR1) was 100%. Because the concentration of carbon dioxide in the gas was 30% by volume, the reaction time was longer, but the carbon dioxide utilization rate (UR1) remained at 100%.

[0123] The various conditions and results are shown in Tables 1 and 2.

[0124] (Example 3)

[0125] use Figure 2The apparatus of the second embodiment shown is the same as in Example 1, except that a YJ nozzle is used instead of a vortex turbine mixing pump to generate carbon dioxide bubbles. The YJ nozzle used is the YJ-6 inline type (trade name).

[0126] First, 800g of sodium carbonate powder and 4000g of ion-exchange water were added to an 8L sodium carbonate aqueous solution concentration adjustment tank 1 and stirred to obtain 4800g of a 16.7% sodium carbonate aqueous solution. Next, this aqueous solution was transferred to an 8L sodium bicarbonate precipitation tank 6, and the magnetic pump 26 was started, circulating the solution using the circulation piping 10. A stainless steel motor pump MM-254 (trade name) manufactured by MALHATY PUMP MFG.CO.,LTD. was used as the magnetic pump. The circulation flow rate was 20L / min. After the initial circulation, carbon dioxide gas was supplied to the YJ nozzle 28 at a rate of 1.0L / min, and the carbon dioxide was microbubbled before being introduced. The carbon dioxide bubble size was d50=63μm, d90=102μm. The temperature of the aqueous solution during carbon dioxide introduction was 25~35℃. 169 minutes after the start of carbon dioxide-containing bubble supply, the sodium bicarbonate precipitation tank becomes a cloudy sodium bicarbonate slurry with pH=8.0. The carbon dioxide utilization rate (UR1) = 100%.

[0127] The sodium bicarbonate slurry was filtered using a centrifugal dewatering machine 13, yielding 1117 g of centrifugal dewatered filter cake and 4015 g of filtrate. The centrifugal dewatering machine used was a KOKUSAN Co.Ltd. H-110F model. The centrifugal dewatered filter cake was dried at 80°C under a carbon dioxide atmosphere to obtain 893 g of sodium bicarbonate powder.

[0128] On the other hand, the filtrate, saturated sodium bicarbonate solution (concentration 9.3%), was returned to the sodium carbonate aqueous solution concentration adjustment tank 1. After adding 886g of 48% sodium hydroxide aqueous solution, the magnetic pump 25 was started, and circulation was performed using the circulation piping 22. A stainless steel motor pump MM-254 (trade name) manufactured by MALHATY PUMP MFG.CO.,LTD. was used as the magnetic pump. The circulation flow rate was 20L / min. After initial circulation, carbon dioxide gas was supplied to the YJ nozzle 27 at a rate of 1.0L / min, and the carbon dioxide was microbubbled before being introduced. The carbon dioxide bubble size was d50=63μm, d90=103μm. After 69 minutes, the liquid in the sodium carbonate aqueous solution concentration adjustment tank 1 became a sodium carbonate aqueous solution with pH=12.0, weight=5037g, and sodium carbonate content=800g. The carbon dioxide utilization rate (UR2)=100%.

[0129] Next, the magnetic pump 25 is started, and the circulation piping 22 is used to circulate the solution at a flow rate of 20 L / min. Air is supplied to the YJ nozzle 27 at a rate of 1.0 L / min, and the air is introduced after being microbubbled. The sodium carbonate aqueous solution in the concentration adjustment tank 1 is gradually concentrated through the evaporation of water. After 9 hours, the weight of the sodium carbonate aqueous solution is 4800 g. The sodium carbonate content is 800 g, which is the same as the content of the initially prepared sodium carbonate aqueous solution.

[0130] The various conditions and results are shown in Tables 1 and 2.

[0131] (Example 4)

[0132] In the sodium bicarbonate precipitation tank 6, the supply rate of carbon dioxide added to the YJ nozzle 28 was changed to 3.0 L / min, otherwise, it was carried out in the same manner as in Example 3. The size of the carbon dioxide bubbles was d50 = 65 μm and d90 = 108 μm. The temperature of the aqueous solution when introducing carbon dioxide was 25~35°C. 56 minutes after the start of supplying carbon dioxide-containing bubbles, the sodium bicarbonate precipitation tank became a cloudy sodium bicarbonate slurry with pH = 8.0. Even with an increased carbon dioxide supply flow rate, the reaction could proceed at a high speed with a carbon dioxide utilization rate (UR2) of 100%.

[0133] The various conditions and results are shown in Tables 1 and 2.

[0134] (Example 5)

[0135] In the sodium bicarbonate precipitation tank 6, the supply rate of carbon dioxide added to the YJ nozzle 28 was changed to 5.0 L / min, otherwise, it was carried out in the same manner as in Example 3. The size of the carbon dioxide bubbles was d50 = 72 μm and d90 = 124 μm. The temperature of the aqueous solution when introducing carbon dioxide was 25~35°C. 34 minutes after the start of supplying carbon dioxide-containing bubbles, the sodium bicarbonate precipitation tank became a cloudy sodium bicarbonate slurry with pH = 8.0. Even with an increased carbon dioxide supply flow rate, the reaction could proceed at a high speed with a carbon dioxide utilization rate (UR1) of 100%.

[0136] (Example 6)

[0137] 800g of sodium carbonate powder and 4000g of ion-exchanged water were added to an 8L sodium bicarbonate precipitation tank 6 and stirred to obtain 4800g of a 16.7% sodium carbonate aqueous solution. Next, in the sodium bicarbonate precipitation tank 6, carbon dioxide was blown out and added at a rate of 1.0L / min using a cylindrical gas injection pipe (trade name: KERAMI FILTER, orifice size: 50μm) manufactured by Koshin Rikka Co., Ltd., instead of using a vortex turbine mixing pump 9 and a YJ nozzle 28 for microbubbling and carbon dioxide addition. The carbon dioxide bubbles were large, with d50=168μm and d90=306μm. The temperature of the aqueous solution when introducing carbon dioxide was 25~35℃. It took 277 minutes for the liquid in the sodium bicarbonate precipitation tank to become a cloudy sodium bicarbonate slurry with pH=8.0, and the carbon dioxide utilization rate (UR1) was 61%.

[0138] The various conditions and results are shown in Tables 1 and 2.

[0139] (Example 7)

[0140] 800g of sodium carbonate powder and 4000g of ion-exchanged water were added to an 8L sodium bicarbonate precipitation tank 6 and stirred to obtain 4800g of a 16.7% sodium carbonate aqueous solution. Next, a 4mm diameter stainless steel tube was placed inside the sodium bicarbonate precipitation tank 6, and carbon dioxide was added at a rate of 1.0L / min, instead of using a vortex turbine mixing pump 9 and a YJ nozzle 28 for microbubbling before adding carbon dioxide. The size of the carbon dioxide bubbles in the sodium bicarbonate aqueous solution was several mm to several tens of mm visually. The temperature of the aqueous solution when introducing carbon dioxide was 25~35℃. Carbon dioxide was added for 169 minutes, similar to Example 1, but the pH of the liquid in the sodium bicarbonate precipitation tank reached 10.0, there was no turbidity, and no sodium bicarbonate was precipitated. The various conditions and results are shown in Tables 1 and 2.

[0141] (Example 8)

[0142] In Example 7, the addition of carbon dioxide continued even after 169 minutes. The temperature of the aqueous solution during carbon dioxide introduction was 25-35°C. The liquid in the sodium bicarbonate precipitation tank became a cloudy sodium bicarbonate slurry with a pH of 8.0, which was very time-consuming, taking up to 1020 minutes. The carbon dioxide utilization rate (UR1) was 17%.

[0143] The various conditions and results are shown in Tables 1 and 2.

[0144] [Table 1]

[0145]

[0146] [Table 2]

[0147]

[0148] (Example 9)

[0149] use Figure 1 The apparatus of the first embodiment shown uses potassium salt instead of sodium salt. First, 835g of potassium carbonate and 1600g of ion-exchange water are added to a concentration adjustment tank 1 with an internal volume of 8L and stirred to obtain 2435g of a potassium carbonate aqueous solution with a concentration of 34.3%. Next, this aqueous solution is transferred to a precipitation tank 6 with an internal volume of 8L, and a vortex turbine mixing pump 9 is started, circulating the solution using a circulation pipe 10. A Nikuni Co., Ltd. KTM15ND02S type vortex turbine mixing pump is used. The circulation flow rate is 20L / min. After the initial circulation, carbon dioxide gas is supplied to the suction pipe side of the vortex turbine mixing pump 9 at a rate of 1.0L / min, and the carbon dioxide is microbubbled before being introduced. The carbon dioxide bubble size is d50=63μm, d90=107μm. The temperature of the aqueous solution when introducing carbon dioxide is 25~35°C. After 136 minutes, the sodium bicarbonate precipitation tank contains a turbid potassium bicarbonate slurry with a pH of 8.3. Carbon dioxide utilization rate (UR1) = 100%.

[0150] The potassium bicarbonate slurry was filtered using a centrifugal dewatering machine 13, yielding 668 g of centrifugal dewatered filter cake and 2033 g of filtrate. The centrifugal dewatering machine used was a KOKUSAN Co.Ltd. H-110F model. The centrifugal dewatered filter cake was dried at 80°C under a carbon dioxide atmosphere to obtain 605 g of potassium bicarbonate powder.

[0151] On the other hand, the filtrate, a saturated potassium bicarbonate solution (concentration 29.8%), was returned to concentration adjustment tank 1. After adding 706g of a 48% potassium hydroxide aqueous solution, the vortex turbine mixing pump 4 was started, and circulation was achieved using circulation piping 22 at a flow rate of 20L / min. Air was supplied to the suction side of the vortex turbine mixing pump 4 at a rate of 1.0L / min, causing the air to be microbubbled before introduction. The potassium carbonate aqueous solution in concentration adjustment tank 1 gradually concentrated through water evaporation. After 12 hours, the weight of the potassium carbonate aqueous solution became 2435g. The potassium carbonate content was 835g, the same as the content in the initially prepared potassium carbonate aqueous solution.

[0152] The various conditions and results are shown in Tables 3 and 4.

[0153] [Table 3]

[0154]

[0155] [Table 4]

[0156]

[0157] (Example 10)

[0158] The average particle size d50 of general industrial sodium bicarbonate (product name: KF) manufactured by AGC Inc. is 150 μm. Using the same pulverizer as in Example 1, 200 g of this powder was pulverized for 30 minutes at a blade speed of 4,000 rpm, and the average particle size d50 could only be reduced to 33 μm. Therefore, a second pulverization was performed under the same conditions, resulting in 23 μm, and a third pulverization was performed under the same conditions, finally yielding a fine powder with an average particle size d50 of 13 μm. Compared with the sodium bicarbonate powder of Example 1, this powder is more difficult to pulverize. The relationship between the pulverization conditions and the average particle size of Examples 1 and 10 is shown in Table 5.

[0159] [Table 5]

[0160]

[0161] Explanation of reference numerals in the attached figures

[0162] 1. Concentration adjustment tank for sodium carbonate aqueous solution

[0163] 2.7 Stirring device

[0164] 3. Sodium carbonate aqueous solution

[0165] 4, 9 Vortex Turbine Mixing Pump

[0166] 5. Conveying Piping

[0167] 6 Sodium bicarbonate precipitation tank

[0168] 8. Liquid in the sodium bicarbonate precipitation tank

[0169] 10, 22 Circulation Piping

[0170] 11. Supply piping for gases containing carbon dioxide

[0171] 12. Extraction of sodium bicarbonate slurry

[0172] 13 Centrifugal dehydrator

[0173] 14. Filter cake of sodium bicarbonate obtained by centrifugal dehydration

[0174] 15. Drying equipment

[0175] 16 Sodium bicarbonate powder

[0176] 17 filtrate

[0177] 18 Filtrate Recovery Tank

[0178] 19 Filtrate Transfer Pump

[0179] 20 Filtrate delivery piping

[0180] 21. Sodium hydroxide addition piping

[0181] 23. Supply piping for gases containing carbon dioxide

[0182] 24. Air supply piping

[0183] 25, 26 Magnetic pumps

[0184] 27, 28 YJ nozzles.

Claims

1. A method for producing an alkali metal carbonate or bicarbonate, comprising: A gas bubble containing carbon dioxide, i.e. a carbon dioxide-containing bubble, is supplied to an aqueous solution (a) of at least one alkali metal compound selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal chlorides. In the case where the aqueous solution (a) is an aqueous solution of an alkali metal chloride, carbon dioxide-containing bubbles are supplied after ammonia is supplied to the aqueous solution (a). The size of the carbon dioxide-containing bubbles is less than 100 μm in d50 and less than 150 μm in d90.

2. The method for manufacturing alkali metal carbonates or bicarbonates according to claim 1, wherein, The alkali metal carbonate or bicarbonate is lithium carbonate, sodium carbonate, potassium carbonate, lithium bicarbonate, sodium bicarbonate, or potassium bicarbonate.

3. The method for producing alkali metal carbonates or bicarbonates according to claim 1 or 2, wherein, The concentration of carbon dioxide in the gas containing carbon dioxide is 10% by volume or more.

4. The method for producing alkali metal carbonates or bicarbonates according to claim 1 or 2, wherein, The size of the bubbles containing carbon dioxide is d50 of 50~90μm and d90 of 100~150μm.

5. A method for manufacturing an alkali metal bicarbonate, wherein, The slurry containing alkali metal bicarbonates, obtained by the method for producing alkali metal carbonates or bicarbonates according to claim 1 or 2, is filtered. Add a first aqueous solution (a) of at least one alkali metal compound selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal chlorides to the obtained filtrate to obtain a second aqueous solution (a). Carbon dioxide-containing bubbles are supplied to the second aqueous solution (a) to obtain a third aqueous solution (a) of an alkali metal carbonate or bicarbonate. The solution is concentrated by removing water from the obtained third aqueous solution (a) to obtain the fourth aqueous solution (a). Carbon dioxide-containing bubbles are supplied to the resulting fourth aqueous solution (a), thereby causing the alkali metal bicarbonate to precipitate.

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