WO2025127743A1 - Methods for producing gypsum and sodium bicarbonate with controlled particle size using sodium sulfate and apparatus for producing sodium bicarbonate - Google Patents

Abstract

The present invention relates to methods for producing gypsum and sodium bicarbonate with controlled particle size using sodium sulfate, and an apparatus for producing sodium bicarbonate and, more specifically, to: a method for producing sodium bicarbonate, comprising the steps of producing a sodium sulfate solution containing sodium ions from a mixture of a leaching agent and a sodium sulfate-containing material, producing sodium bicarbonate (NaHCO₃) by adding carbon dioxide and ammonia into the sodium sulfate solution, and controlling the particle size of the sodium bicarbonate by heating the sodium bicarbonate at a temperature of 60-100℃; a method for producing gypsum by adding a calcium-containing material into the filtrate remaining after collecting the sodium bicarbonate in the step of producing the sodium bicarbonate; and a reactor for producing sodium bicarbonate, comprising a leach reactor in which a sodium aqueous solution is produced by leaching sodium ions from a sodium sulfate-containing material by using a leaching agent, a carbonation reactor in which a gas containing carbon dioxide or a carbonation solution and a gas containing ammonia or an ammonia solution are supplied to the sodium aqueous solution to cause a reaction which produces sodium bicarbonate (NaHCO₃), and a particle size reactor in which the particle size of sodium bicarbonate is coarsened in a sodium bicarbonate-generating aqueous solution at 60-100℃.

Description

Method for manufacturing particle-sized sodium bicarbonate and gypsum using sodium sulfate and sodium bicarbonate manufacturing device

The present invention relates to a method for manufacturing sodium bicarbonate and gypsum with controlled particle size using sodium sulfate and a related manufacturing device, and more specifically, to a method for manufacturing sodium bicarbonate and gypsum capable of controlling the particle size of sodium bicarbonate, including a process capable of controlling the particle size during the sodium bicarbonate manufacturing process, and a sodium bicarbonate manufacturing device.

Flue gas desulfurization refers to the removal of sulfur (S) components, especially sulfur dioxide ( _SO2 ), in exhaust gases emitted from steel mills, thermal power plants, etc. With the development of industry, harmful gases such as sulfur oxides ( _SOx ) emitted from various factories, thermal power plants, and incinerators are causing serious air pollution and inducing various diseases such as respiratory diseases, asthma, and lung cancer in the human body. Desulfurizing agents currently used in steel mills include sodium bicarbonate ( _NaHCO3 ), activated carbon, and calcium hydroxide (Ca(OH) ₂ ). In particular, sodium bicarbonate is known to exhibit excellent adsorption efficiency when sprayed on high-temperature flue gas because its specific surface area is maximized. At this time, sodium sulfate ( _Na2SO4 ) is generated as a waste product _of the desulfurization process.

Recently, as electric vehicles are becoming more widespread, the demand for lithium, a raw material for secondary batteries, is increasing. The main byproducts generated during lithium production are silica (SiO ₂ ) and sodium sulfate (Na ₂ SO ₄ ). It is expected that the amount of sodium sulfate byproduct generated will also increase in line with the increasing demand for lithium in the future. Therefore, the development of technology that can recycle sodium sulfate is essential for the spread of secondary batteries.

The byproducts currently generated are dissolved in water and then treated as wastewater or are buried as they are, which causes both treatment costs and secondary environmental problems. An effective way to utilize the byproduct sodium sulfate is to dissolve sodium sulfate in water and regenerate it into sodium bicarbonate by injecting carbon dioxide and ammonia.

The technology that forms the basis of this method is the Solvay process, which uses concentrated seawater brine to produce sodium carbonate and calcium chloride ^, while producing sodium bicarbonate as a byproduct. However, the Solvay process does not include a process for treating sulfate ( _SO42- ), so a customized technology development is needed to address this. It is currently predicted that the amount of sodium sulfate generated will continue to increase. Therefore, there is an urgent need for a resource recovery or recycling plan for byproducts such as sodium sulfate.

One embodiment of the present invention provides a method for producing sodium bicarbonate having a controlled particle size using a material containing sodium sulfate.

Another embodiment of the present invention provides a method for manufacturing gypsum using a particle size-controlled sodium bicarbonate.

Another embodiment of the present invention provides a device for manufacturing a particle size-controlled sodium bicarbonate using the same.

According to one embodiment of the present invention, a method for producing sodium bicarbonate is provided, comprising: a step of producing a sodium sulfate solution containing sodium ions from a mixture of a dissolving agent and a sodium sulfate-containing material; a step of adding carbon dioxide and ammonia to the sodium sulfate solution to produce sodium bicarbonate (NaHCO ₃ ); and a step of controlling the particle size of the sodium bicarbonate by cooling at a temperature lower than that in the step of producing the sodium bicarbonate.

According to another embodiment of the present invention, a method for producing gypsum is provided, which further includes a step of producing gypsum by recovering the gypsum in the step of producing the gypsum and adding a calcium-containing material to the remaining residue.

According to another embodiment of the present invention, a reactor for producing sodium bicarbonate is provided, comprising: an elution reactor for eluting sodium ions from a sodium sulfate-containing material by a eluting agent to produce a sodium aqueous solution; a carbonation reactor for supplying a carbon dioxide-containing gas or a carbonation solution and an ammonia-containing gas or an ammonia solution to the sodium aqueous solution and producing sodium bicarbonate (NaHCO ₃ ) through a reaction; and a particle size reactor for coarsenting the particle size of the sodium bicarbonate-produced aqueous solution at 35 to 100° C.

According to the present invention, it is possible to manufacture sodium bicarbonate having an adjusted particle size by using a material containing sodium sulfate, a sodium sulfate byproduct, or desulfurization waste from a steel mill or a power plant, and further, by producing gypsum using waste liquid, the landfill cost of waste generated after desulfurization is reduced, and by stably fixing carbon dioxide as a carbonate, there is an effect of contributing to carbon neutrality as a CCU technology for carbon dioxide use.

Figure 1 schematically illustrates an exemplary process flow diagram of the present invention.

Figure 2 is a graph showing the yield of sodium bicarbonate (graph corresponding to the y-axis on the right) and purity (graph corresponding to the y-axis on the left) according to the carbonation reaction temperature.

Figure 3 is a graph showing the ammonia recovery rate (%) according to the amount of CaO added (mL) per 100 mL of wastewater produced after the carbonation reaction.

Figure 4 is a graph showing the ratio of the weight of gypsum recovery to the weight of sodium sulfate according to the amount (mL) of quicklime (calcium oxide, CaO) added per 100 mL of wastewater produced after the carbonation reaction, i.e., the gypsum yield.

Figure 5 is a graph showing the particle size (㎛) of the produced sodium bicarbonate according to the temperature of the particle size distribution reactor.

Figure 6 schematically illustrates an exemplary reactor for producing a mixed salt of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a method for producing sodium bicarbonate (NaHCO ₃ ) with controlled particle size, and further to a method for producing gypsum (CaSO ₄ ) using the same. The present invention aims to provide a method and a related device for producing sodium bicarbonate by recovering sodium (Na) from low-purity sodium sulfate-containing materials such as sodium sulfate-containing waste or natural minerals, thereby producing sodium bicarbonate, and producing high-purity gypsum from SO ₄ ^2- waste liquid, thereby reducing the landfill cost of waste generated after desulfurization, and stably fixing carbon dioxide as a carbonate to produce sodium bicarbonate and gypsum.

The method for producing sodium bicarbonate of the present invention comprises the steps of producing a sodium sulfate solution containing sodium ions from a mixture of a dissolving agent and a sodium sulfate-containing material; the step of adding carbon dioxide and ammonia to the sodium sulfate solution to produce sodium bicarbonate (NaHCO ₃ ); and the step of cooling the sodium bicarbonate at a temperature lower than that in the step of producing the sodium bicarbonate to control the particle size of the sodium bicarbonate.

Figure 1 schematically illustrates an exemplary process flow diagram of the present invention, wherein the above-described reaction can be performed through a dissolution reactor (100), a carbonation reactor (200), and a particle sizer reactor (300).

More specifically, the step of generating a sodium sulfate solution containing sodium ions from a mixture of a dissolving agent (101) and a sodium sulfate-containing material, for example, sodium sulfate waste (102), may be performed by a solid-liquid separation step of generating and recovering a sodium sulfate solution containing sodium ions from the mixture of the dissolving agent and the sodium sulfate-containing material and discharging the waste (103). This reaction may be performed in a dissolution reactor (100).

The step of generating the sodium sulfate solution containing the above sodium ions is a step of generating and recovering the sodium sulfate solution from a sodium sulfate-containing material by a dissolving agent. A stirring step of mixing the sodium sulfate-containing material and the dissolving agent may be further included before the step of generating the sodium sulfate solution containing the above sodium ions. Since the dissolving agent contains almost no sodium ions, the sodium sulfate solution can be easily generated from the sodium sulfate-containing material.

The sodium sulfate-containing material may be a sodium sulfate-containing waste, a sodium sulfate-containing material such as natural minerals, etc. For example, the sodium sulfate-containing waste may be generated by desulfurizing flue gas containing sulfur oxide (SO _x ) components with sodium bicarbonate, or may be waste generated as a byproduct in a lithium production plant. For example, it may be generated by desulfurizing flue gas generated by combustion in a thermal power plant, factory, or incinerator using sodium bicarbonate, or flue gas generated by electrostatic precipitation in a steel mill sintering plant. The sodium sulfate-containing waste contains impurities such as K, Ca, Fe, and Cl in addition to sodium sulfate, so that the solid impurities generated after the stirring is completed can be removed in the solid-liquid separation step.

The solubility of sodium sulfate at room temperature is 28.1 g/100 mL, and the solubility changes rapidly as the temperature increases in the temperature range of 5 to 45°C, so the appropriate dissolution temperature for desulfurized waste is between 20 and 60°C.

The above eluting agent is not particularly limited as long as it is a substance that can elute sodium sulfate ions when combined with a sodium sulfate-containing substance, but may be, for example, one or more selected from water and an aqueous ammonia solution.

The step of generating sodium bicarbonate (NaHCO ₃ ) by adding carbon dioxide, for example, a carbon dioxide-containing gas (201) and ammonia gas and/or solution (202) to the above sodium sulfate solution may be performed including an ammonification step of adding ammonia to the sodium sulfate solution and a carbonation step of adding carbon dioxide, and such carbonation step may be performed in a carbonation reactor (200).

The above sodium sulfate solution can react with carbon dioxide and ammonia to produce solid sodium bicarbonate through a carbonation reaction of the following formula (1).

Na ₂ SO ₄ + 2CO ₂ + 2NH ₃ + 2H ₂ O → 2NaHCO ₃ + (NH ₄ ) ₂ SO ₄ Equation (1)

As shown in the above equation 1, the Gibbs free energy of the reaction that produces calcium carbonate is -851.0 kJ/mol, which is a negative number, so the reaction that produces sodium bicarbonate can occur spontaneously. In addition, since this reaction is an exothermic reaction, there is an advantage in that additional energy consumption during the sodium bicarbonate production process is not much.

The reaction pressure of the carbonation reactor in which the above carbonation reaction occurs may be 1 to 10 atm, and the reaction temperature may be 120°C or lower, or 80°C or lower. For example, a step of heating the sodium sulfate solution of the carbonation reactor to 40 to 120°C and injecting carbon dioxide and ammonia to produce sodium bicarbonate (NaHCO ₃ ) may be performed. When the pressure of the carbonation reactor exceeds 10 atm, a sufficient amount of carbon dioxide can be dissolved, but the energy required for the carbonation reactor is high, which reduces the economic feasibility of the final products, sodium bicarbonate and gypsum. The time of the carbonation reaction varies depending on the method of injecting carbon dioxide.

Meanwhile, if the temperature of the carbonation reactor is lower than 40°C, the purity may be insufficient, and if it exceeds 120°C, the yield may tend to decrease.

If carbon dioxide is injected in the form of gas, it can vary depending on whether aeration is performed or not, and if aeration is performed, it can take less than 4 hours. However, the optimized pressure and reaction time can vary depending on the size/space/conditions of the reactor.

The chemical formula of sodium bicarbonate is NaHCO ₃ , and the production of sodium bicarbonate also increases as the concentration of bicarbonate ions (HCO ₃ ^- ) in the solution increases. The concentration of bicarbonate ions in an aqueous solution of a carbonate system containing carbon dioxide is the highest when the pH is 7.5 to 9.0. Therefore, in order to increase the recovery rate of sodium bicarbonate, it is desirable to maintain the pH of the sodium sulfate solution at 7.5 to 9.0. However, if a sufficient amount of carbon dioxide is dissolved in the sodium sulfate solution to produce the sodium bicarbonate, the pH of the solution may become lower than 7.5. In this case, the bicarbonate ion (HCO ₃ ^- ) is converted to carbonic acid (H ₂ CO ₃ ), which reduces the production rate of sodium bicarbonate. Therefore, it is desirable to first add ammonia before adding carbon dioxide to the sodium sulfate solution to sufficiently dissolve it, and then add the carbon dioxide.

The above carbon dioxide may be at least one selected from the group consisting of pure carbon dioxide, FINEX off gas (FOG), FINEX tail gas (FTG), blast furnace gas (BFG), converter gas, coal-fired power plant exhaust gas, gas-fired power plant exhaust gas, incinerator exhaust gas, glass melting exhaust gas, thermal facility exhaust gas, petrochemical process exhaust gas, petrochemical process gas, pre-combustion exhaust gas, and gasifier exhaust gas. In addition, the carbon dioxide may be concentrated by at least one method selected from the group consisting of a wet amine process, a PSA process, and a membrane process.

Meanwhile, the recovery rate of sodium bicarbonate can be adjusted by controlling the mass ratio of the sodium sulfate-containing material to be input and the water as the eluent. That is, in order for the recovery rate of the recovered sodium bicarbonate to be 50% (based on Na ⁺ mole) or more, the mass ratio of the sodium sulfate-containing material to be input and the eluent may be 1:1.5 to 1:5, preferably 1:1.75 to 3.0. If the water ratio is too low, below the above range, the desulfurization waste is not dissolved, resulting in a large amount of residue, which reduces the recovery rate of sodium, and if the water ratio is too high, exceeding the above range, the recovery rate of sodium increases, but the cost of wastewater treatment in the subsequent process increases. Within the scope of the present invention, 80% or more of the sodium contained in the desulfurization waste can be recovered, and the amount of undissolved desulfurization waste after separation and drying is less than 10% of the initial input amount, and the amount of undissolved desulfurization waste decreases as the amount of water increases.

Meanwhile, in order to recover 50 mol% of sodium bicarbonate based on the molar concentration of Na ⁺ , the molar ratio of ammonia ( _NH3 )/sodium (Na ⁺ ) in the waste solution is preferably 0.8 to 1.3. If the molar ratio of ammonia ( _NH3 )/sodium (Na ⁺ ) is less than 0.8, the recovery rate of sodium bicarbonate recovered in the second solid-liquid separation step (S5) is less than 50 mol%, and if it exceeds 1.3, the recovery rate of sodium bicarbonate increases, but the purity of sodium bicarbonate may decrease.

The present invention comprises a step of heating the sodium sulfate solution to 40 to 120°C and adding carbon dioxide and ammonia to produce sodium bicarbonate (NaHCO3), followed by a step of cooling the sodium bicarbonate at a temperature lower than the step of producing the sodium bicarbonate to control the particle size of the sodium bicarbonate.

The step of controlling the particle size of the above-mentioned sodium bicarbonate may be performed in a particle sizer reactor (300), and at this time, the temperature of the particle sizer reactor (300) may be performed at a temperature 5 to 40°C lower than the step of generating sodium bicarbonate (NaHCO ₃ ), for example, at a temperature 10 to 30°C lower. At this time, if the temperature difference is less than 5°C, particle size control of the sodium bicarbonate may not be performed smoothly, and if it exceeds 40°C, there may be a problem of failure in controlling the particle size distribution.

Meanwhile, the temperature of the step of controlling the particle size of the above-mentioned salt may be performed at a temperature of 35 to 100°C, and for example, may be performed at a temperature of 50 to 80°C.

For example, the produced sodium bicarbonate can be manufactured by controlling the temperature using a particle sizer reactor, for example, a rotary circulation reactor, and then producing sodium bicarbonate (301) with a coarse particle size. The step of controlling the particle size of the sodium bicarbonate may be to control the particle size of the sodium bicarbonate to 40 to 250 ㎛, and preferably to control the particle size of the sodium bicarbonate to 50 to 200 ㎛. If the particle size of the sodium bicarbonate is less than 40 ㎛, it is difficult to handle due to flying, and there is a problem that it is difficult to control the input amount of the sodium bicarbonate in a process using the sodium bicarbonate as a raw material.

At this time, it is preferable that the cooling rate be performed at 2 to 20 ℃/hour. If the cooling rate is less than the above range, the cooling rate becomes slow and particle size control may not be performed smoothly. If the cooling rate exceeds the above range, crystals are quickly formed and there is a problem with particle size distribution control. Meanwhile, if the temperature can be lowered at a sufficient temperature reduction rate in the carbonation reactor, the particle size reduction reactor may be omitted.

In the step of producing sodium bicarbonate (NaHCO ₃ ) by adding carbon dioxide and ammonia to the sodium sulfate solution, if the separated sodium bicarbonate is produced using a sodium sulfate-containing material containing impurities, the purity of sodium bicarbonate may be lower than that of the sodium bicarbonate produced with pure sodium sulfate, so a sodium bicarbonate washing step may be additionally performed to increase the purity of the sodium bicarbonate. As the amount of washing in the sodium bicarbonate washing step increases, the purity of the produced sodium bicarbonate can be improved.

At this time, washing can be performed with 0.5 to 4 parts by weight of water per 1 part by weight of the sodium bicarbonate. If the water is below the above range, the purity may be insufficiently improved, and if it exceeds the above range, the sodium bicarbonate recovery rate may be reduced.

In addition, the washed sodium bicarbonate may further include a sodium bicarbonate drying step. Since the sodium bicarbonate drying step is performed at a temperature exceeding 50°C, the sodium bicarbonate tends to be decomposed again into sodium carbonate, so it is preferable that the drying of the sodium bicarbonate is performed at 50°C or lower.

However, if the final target product is sodium carbonate rather than sodium bicarbonate, the sodium bicarbonate produced can be dried at 50℃ or higher to obtain sodium carbonate. In addition, the solution used for washing to improve the purity of sodium bicarbonate can be recycled as a dissolving agent.

According to another embodiment of the present invention, a method for producing gypsum is provided, which further includes a step of recovering the sodium bicarbonate in the step of producing the sodium bicarbonate and adding a calcium-containing material (401) to the remaining residue to produce gypsum (402), and this step can be performed in a gypsum reactor (400). More specifically, since the residue produced after the carbonation reaction contains a large amount of sulfate ions (SO ₄ ^2- ), a calcium-containing material can be added to produce the sulfate ions contained in the residue into gypsum.

The above calcium-containing material may be at least one selected from the group consisting of waste cement, waste concrete, coal ash, fly ash, iron ore slag, quicklime (CaO), calcium chloride (CaCl ₂ ), wollastonite, limestone, olivine, serpentine, asbestos, and deinking ash.

When a calcium-containing substance is added to the filtrate whose pH is optimized between 7.5 and 9.0 to produce the above-mentioned sodium bicarbonate, the pH of the filtrate rises to 9 or higher. When the pH of the filtrate becomes 9 or higher, the carbon dioxide remaining in the solution exists in the form of carbonate ions (CO ₃ ^2- ), so the added calcium ions (Ca ²⁺ ) react with the carbonate ions to produce calcium carbonate (CaCO ₃ ). In addition, the carbon dioxide remaining in the solution in a high pH state forms slaked lime (Ca(OH) ₂ ) by hydroxyl groups (OH ^- ) in water.

Furthermore, the present invention may further include an ammonia recovery step of recovering gypsum in the step of generating gypsum in a device additionally equipped with an ammonia recovery reactor (500), heating the remaining filtrate to generate ammonia, and discharging the filtrate (501). More specifically, since wastewater produced after a carbonation reaction contains a large amount of ammonia, it is desirable to recover it. At this time, in order to secure an ammonia recovery rate of 50% or more, the temperature and pH of the reactor should be 60°C and pH 8.0 or higher, respectively.

That is, it is preferable that the pH of the ammonia recovery step be maintained at 8.0 or higher. If the pH of the ammonia recovery step is lower than 8.0, there is a problem that the ammonia recovery rate is low. In addition, the ammonia recovery step heats the remaining filtrate, and if the temperature of the heated filtrate is lower than 60°C, there is a problem that the ammonia recovery rate is low. For example, the temperature of the ammonia recovery step may be 60 to 100°C.

In order to increase the pH of the waste solution, the manufactured lime slurry can be injected, and it can also be injected in powder form rather than slurry form. When the lime slurry is injected and the temperature of the waste solution increases, ammonia gas is generated simply by stirring. However, a solution injection method, etc. can be applied to shorten the recovery rate and recovery time of ammonia. The ammonia gas generated in this way can be injected directly into the carbonation reactor or dissolved in water again to create ammonia water and injected into the carbonation reactor.

At this time, the molar ratio of calcium ions and sulfate ions (Ca ²⁺ : SO ₄ ^2- ) is preferably 1: 1.0 to 1.3. If the ratio of sulfate ions exceeds 1.3, the purity of the gypsum decreases, and if the ratio of sulfate ions is less than 1.0, the pH of the filtrate is too low, which causes a problem in that ammonia cannot be sufficiently recovered in the ammonia stripping step.

The calcium-containing material reacts with water, causing an exothermic reaction. Therefore, by adding a heat exchanger between the sodium bicarbonate reactor and the ammonia recovery equipment, additional energy consumption can be reduced by applying heat to the ammonia recovery equipment, thereby saving energy in the ammonia recovery step.

The above recovered ammonia can be reused in the form of gas or remanufactured into ammonia water and then reused.

The above calcium-containing material may be at least one selected from the group consisting of waste cement, waste concrete, coal ash, fly ash, iron ore slag, quicklime (CaO), calcium chloride (CaCl ₂ ), wollastonite, limestone, olivine, serpentine, asbestos, and deinking ash.

At this time, the quicklime (CaO) may be added in a volume of 10 to 50 mL per 100 mL of wastewater produced after the carbonation reaction.

According to another embodiment of the present invention, there is provided an apparatus which can be used for producing sodium bicarbonate and gypsum according to the present invention described above. Fig. 6 schematically illustrates an exemplary reactor for producing sodium bicarbonate of the present invention.

More specifically, according to the present invention, a reactor for producing sodium bicarbonate is provided, comprising: a dissolution reactor (S1) for dissolving sodium ions from a sodium sulfate-containing material by a dissolution agent to produce a sodium aqueous solution; a carbonation reactor (S2) for supplying a carbon dioxide-containing gas or a carbonation solution and an ammonia-containing gas or an ammonia solution to the sodium aqueous solution and producing sodium bicarbonate (NaHCO ₃ ) through a reaction; and a particle size reactor (S3) for coarsenting the particle size of the sodium bicarbonate-produced aqueous solution at 35 to 100°C, for example, 40 to 80°C.

In the above-mentioned dissolution reactor, a step of generating a sodium sulfate solution containing sodium ions from a mixture of a dissolution agent and a sodium sulfate-containing material is performed, in a carbonation reactor, a step of generating sodium bicarbonate (NaHCO ₃ ) by a reaction is performed by supplying a carbon dioxide-containing gas or a carbonation solution and ammonia-containing gas or an ammonia solution to a sodium aqueous solution is performed, and in a particle size reactor, a step of controlling the particle size of the sodium bicarbonate by cooling the sodium bicarbonate at a temperature of 35 to 100° C. is performed. At this time, a reaction of coarsening the particle size of the sodium bicarbonate can be performed for 2 to 10 hours at 35 to 100° C., for example, 40 to 80° C., in the particle size reactor, for example, a circulating reactor.

Furthermore, the reactor for producing sodium bicarbonate of the present invention may additionally include an ammonia recovery reactor in which a calcium-containing material is supplied to the remaining filtrate after recovering sodium bicarbonate to generate gaseous ammonia; and an evaporation and concentration reactor in which the filtrate of the ammonia recovery reactor is supplied and gypsum is generated through evaporation and concentration.

At this time, each reaction occurring in each reactor is as described above.

Hereinafter, the present invention will be described more specifically through specific examples. The following examples are merely examples to help understand the present invention, and the scope of the present invention is not limited thereto.

Example

Example 1: Preparation of the sodium bicarbonate

100 g of desulfurization waste containing sodium sulfate ( _Na2SO4 ) as a _by -product of desulfurization treatment and 175 mL of water were added and stirred at a stirring speed of 500 rpm for 1 hour at 40°C. After stirring, the mixture was filtered to separate solid and liquid and recover the sodium leached solution.

Next, in order to synthesize sodium bicarbonate, 75 mL of sodium leached solution and 25 mL of 25 wt% ammonia aqueous solution were injected into a 300 mL high-pressure reactor. The temperature was maintained at 25°C, and carbon dioxide gas was injected at 7 bar. At this time, the stirring speed was set to 200 rpm, and the reaction time was 8 hours.

When the reaction is completed, sodium bicarbonate is generated as a white solid precipitate, and this is subjected to solid-liquid separation through filtration. The sodium bicarbonate obtained in this way is dried at room temperature. When sodium bicarbonate is heated to a temperature of 50℃ or higher during the carbonation reaction, it decomposes into sodium carbonate, and the purity increases and the yield decreases.

If necessary, a washing process can be performed to increase the purity of the sodium bicarbonate. Meanwhile, Fig. 2 is a graph showing the yield and purity of the sodium bicarbonate according to the temperature. More specifically, the reaction was performed at a pressure of 7 bar under _{a CO2} atmosphere for 60 minutes at each temperature of 40℃, 60℃, 80℃, and 100℃ in the carbonation reactor. The purity of the sodium bicarbonate was confirmed through X-ray diffraction analysis (XRD) and elemental analysis.

The reaction results of 100 g of desulfurized waste are summarized in Table 1 below.

[Table 1]

Example 2: Preparation of plaster

To determine the ammonia recovery rate in an ammonia recovery reactor after the manufacture of gypsum, 100 mL of waste solution after carbonation was placed in the reactor, heated to 80°C, and then 7 M CaO slurry was added. Next, nitrogen was used for aeration.

Furthermore, the gypsum was recovered and the remaining residue was evaporated by heating to recover ammonia. At this time, the recovery rate of ammonium was confirmed through IC, and the results are shown in Fig. 3.

one side, After recovering gypsum and evaporating and concentrating the remaining solution, the amount of gypsum produced according to the amount of CaO added during ammonia recovery was measured. At this time, the concentration was performed by putting the waste solution after ammonia stripping into a reactor and evaporating and concentrating at 80°C. Finally, the mass of the remaining solid was measured, and the yield of gypsum (CaSO ₄ ) is shown in Fig. 4.

In the graphs of Figures 3 and 4, the x-axis represents the volume of 7M quicklime (CaO) per 100 mL of the residue (waste liquid) generated after carbonation.

Experimental Example 1: Particle size of sodium bicarbonate according to reaction temperature

In Example 1, the temperature of the carbonation reactor was heated to 40 to 100°C to increase the particle size. The sodium bicarbonate solution reacted in the carbonation reactor was transferred to a particle sizer reactor for precipitation. The particle sizer reactor was a circulating reactor, and the temperature fed from the carbonation reactor to the particle sizer reactor was controlled to 60 to 100°C. In the circulating reactor, a cooling process was performed to precipitate and coarsen the sodium bicarbonate crystals, and the temperature of the circulating sodium bicarbonate solution was controlled to 40 to 70°C, which is lower than the temperature at which sodium bicarbonate is generated in the carbonation reaction.

In more detail, the sodium bicarbonate solution was circulated for 60 minutes at each temperature of 40℃, 60℃, 80℃, and 100℃ in the carbonation reactor, and the sodium bicarbonate particle size was measured after cooling to 40℃ in the circulating reactor, and the results are shown in Fig. 5. The particle size reactor consists of a cooling reactor and a room temperature reactor, and the sodium bicarbonate solution is injected into the room temperature reactor and then circulated to the cooling reactor.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible within a scope that does not depart from the technical spirit of the present invention described in the claims.

[Explanation of symbols]

100: Dissolution reactor

101: Dissolution agent 102: Sodium sulfate waste 103: Waste

200: Carbonation reactor

201: Carbon dioxide containing gas 202: Ammonia gas or solution

300: Particle size reactor

301: Medium

400: Gypsum Reactor

401: Calcium-containing substances 402: Gypsum

500: Ammonia recovery reactor

501: Balance

Claims (14)

A step of producing a sodium sulfate solution containing sodium ions from a mixture of a dissolving agent and a sodium sulfate-containing material; A step of heating the above sodium sulfate solution to 40 to 120°C and adding carbon dioxide and ammonia to produce sodium bicarbonate (NaHCO ₃ ); and A step of controlling the particle size of the sodium bicarbonate by cooling the sodium bicarbonate at a temperature lower than that in the step of generating the sodium bicarbonate; A method for manufacturing a sodium bicarbonate, comprising: A method for producing sodium bicarbonate, wherein in the first paragraph, the temperature of the step of controlling the particle size of the sodium bicarbonate is performed at a temperature 5 to 40°C lower than that of the step of producing sodium bicarbonate (NaHCO ₃ ). A method for manufacturing sodium bicarbonate, wherein the temperature of the step of controlling the particle size of the sodium bicarbonate in the first paragraph is performed at a temperature of 35 to 75°C. A method for producing sodium bicarbonate, wherein the pH of the sodium sulfate solution in claim 1 is 7.5 to 9.0. A method for manufacturing sodium bicarbonate, wherein in the step of controlling the particle size of the sodium bicarbonate in the first paragraph, the particle size of the sodium bicarbonate is controlled to 40 to 250 ㎛. A method for producing sodium bicarbonate, further comprising the step of washing the sodium bicarbonate with 0.5 to 4 parts by weight of water per 1 part by weight of the sodium bicarbonate in the first paragraph. A method for producing gypsum, wherein in the first paragraph, the method further comprises a step of recovering the sodium bicarbonate in the step of producing the sodium bicarbonate and adding a calcium-containing material to the remaining residue to produce gypsum. A method for manufacturing gypsum, wherein in the step of generating the sodium bicarbonate, the sodium bicarbonate is recovered and the remaining solution has a pH adjusted to 7.5 to 9.0. A method for producing gypsum, in claim 7, further comprising an ammonia recovery step of recovering gypsum in the step of producing gypsum and heating the remaining residue to 60°C or higher to produce ammonia. A method for manufacturing gypsum, wherein the calcium-containing material in claim 7 is quicklime (CaO). A method for manufacturing gypsum, wherein in claim 10, the quicklime (CaO) is added in a volume of 10 to 50 mL per 100 mL of wastewater produced after a carbonation reaction. A dissolution reactor for producing a sodium aqueous solution by dissolving sodium ions from a sodium sulfate-containing material using a dissolution agent; A carbonation reactor in which carbon dioxide-containing gas or a carbonation solution and ammonia-containing gas or ammonia solution are supplied to the sodium aqueous solution and sodium bicarbonate (NaHCO ₃ ) is generated by reaction; and A reactor for producing sodium bicarbonate, comprising a particle size reactor for coarsenting the particle size of sodium bicarbonate in a sodium bicarbonate producing aqueous solution at 35 to 100°C. A reactor for producing sodium bicarbonate, further comprising an ammonia recovery reactor in which a calcium-containing substance is supplied to the remaining residue after recovering sodium bicarbonate to generate gaseous ammonia. A reactor for producing sodium bicarbonate, further comprising an evaporation and concentration reactor in which the ammonia recovery reactor filtrate is supplied and gypsum is produced through evaporation and concentration in the 13th paragraph.

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