Methods for producing gypsum and sodium bicarbonate with controlled particle size using sodium sulfate and apparatus for producing sodium bicarbonate

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 apparatus

[0001] 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.

[0002] Flue gas desulfurization refers to the removal of sulfur (S) components, especially sulfur dioxide (SO2), from exhaust gases emitted from steel mills, thermal power plants, etc. With the development of industry, sulfur oxides (SO2) emitted from various factories, thermal power plants, incinerators, etc. x ) cause serious air pollution and induce various diseases in the human body such as respiratory diseases, asthma, and lung cancer. Currently, desulfurizing agents used in steel mills include sodium bicarbonate (NaHCO3), activated carbon, and calcium hydroxide (Ca(OH)2), and in particular, sodium bicarbonate is known to exhibit excellent adsorption efficiency when sprayed on high-temperature exhaust gas due to its maximized specific surface area. At this time, sodium sulfate (Na2SO4) waste is generated as a by-product of the desulfurization process.

[0003] With the recent expansion of electric vehicles, demand for lithium, a raw material for secondary batteries, is increasing. The primary byproducts of lithium production are silica (SiO2) and sodium sulfate (Na2SO4). In line with the growing demand for lithium, the production of sodium sulfate as a byproduct is expected to increase. Therefore, the development of technologies capable of recycling sodium sulfate is essential for the widespread adoption of secondary batteries.

[0004] Currently, byproducts are dissolved in water and then treated as wastewater or directly buried in landfills, resulting in both high treatment costs and secondary environmental problems. One effective way to utilize the byproduct, sodium sulfate, is to dissolve it in water and then inject carbon dioxide and ammonia to regenerate it into sodium bicarbonate.

[0005] The technology underlying this method is the Solvay process, which uses concentrated seawater brine to produce sodium carbonate and calcium chloride, producing baking soda as a byproduct. However, the Solvay process produces sulfate (SO4 2- ) does not include a process for processing sodium sulfate, necessitating the development of customized technologies to address this issue. The current production of sodium sulfate is expected to continue to increase. Therefore, there is an urgent need to develop resource recovery or recycling measures for byproducts such as sodium sulfate.

[0006] One embodiment of the present invention provides a method for producing sodium bicarbonate having a controlled particle size using a material containing sodium sulfate.

[0007] Another embodiment of the present invention provides a method for manufacturing gypsum using a particle size-controlled sodium bicarbonate.

[0008] Another embodiment of the present invention provides a device for manufacturing a particle size-controlled medium.

[0009] 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 producing sodium bicarbonate (NaHCO3) by adding carbon dioxide and ammonia to the sodium sulfate solution; 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.

[0010] 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.

[0011] According to another embodiment of the present invention, a reactor for producing sodium bicarbonate is provided, comprising: a dissolution reactor for dissolving sodium ions from a sodium sulfate-containing material using a dissolution 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 (NaHCO3) 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.

[0012] According to the present invention, it is possible to manufacture sodium bicarbonate having a controlled particle size using a material containing sodium sulfate, a sodium sulfate byproduct, or desulfurization waste from a steel mill or 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 into carbonate, it has the effect of contributing to carbon neutrality as a CCU technology for carbon dioxide use.

[0013] Figure 1 schematically illustrates an exemplary process flow diagram of the present invention.

[0014] 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.

[0015] 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.

[0016] Figure 4 is a graph showing the ratio of the weight of gypsum recovered 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.

[0017] Figure 5 is a graph showing the particle size (㎛) of the produced sodium bicarbonate according to the temperature of the particle size reactor.

[0018] Figure 6 schematically illustrates an exemplary reactor for producing a mixed salt of the present invention.

[0019] 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 in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0020] The present invention relates to a method for producing sodium bicarbonate (NaHCO3) with controlled particle size and further to a method for producing gypsum (CaSO4) using the same, wherein sodium (Na) is recovered from low-purity sodium sulfate-containing materials such as sodium sulfate-containing waste or natural minerals to produce sodium bicarbonate, and SO4 2- By producing high-purity gypsum from waste liquid, the landfill cost of waste generated after desulfurization is reduced, and a method and related device for manufacturing baking soda and gypsum by stably fixing carbon dioxide as carbonate are provided.

[0021] 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; adding carbon dioxide and ammonia to the sodium sulfate solution to produce sodium bicarbonate (NaHCO3); and 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.

[0022] 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).

[0023] More specifically, the step of producing 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 producing 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 dissolving reactor (100).

[0024] The step of producing the sodium sulfate solution containing the sodium ions is a step of producing and recovering the sodium sulfate solution from a sodium sulfate-containing material using a dissolving agent. A stirring step of mixing the sodium sulfate-containing material and the dissolving agent may be further included prior to the step of producing the sodium sulfate solution containing the sodium ions. Since the dissolving agent contains almost no sodium ions, the sodium sulfate solution can be easily produced from the sodium sulfate-containing material.

[0025] The above sodium sulfate-containing material may be a sodium sulfate-containing waste or a sodium sulfate-containing material such as natural minerals. For example, sodium sulfate-containing waste may be sulfur oxide (SO x) may be generated by desulfurizing flue gas containing the component with sodium bicarbonate, and may also be waste generated as a by-product in a lithium production plant. For example, it may be generated by desulfurizing flue gas generated by combustion in thermal power plants, factories, incinerators, etc., or flue gas electrostatically precipitated from a steel mill sintering plant using sodium bicarbonate. The above-mentioned 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 above-mentioned stirring can be removed in the solid-liquid separation step.

[0026] 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.

[0027] 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.

[0028] The step of producing sodium bicarbonate (NaHCO3) by adding carbon dioxide, for example, 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).

[0029] 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).

[0030] Na2SO4+ 2CO2+ 2NH3+ 2H2O → 2NaHCO3+ (NH4)2SO4 Formula (1)

[0031] As shown in Equation 1 above, the Gibbs free energy of the reaction that produces calcium carbonate is -851.0 kJ / mol, which is a negative number. Therefore, the reaction that produces sodium bicarbonate can occur spontaneously. Furthermore, since this reaction is an exothermic reaction, it has the advantage of not consuming much additional energy during the sodium bicarbonate production process.

[0032] The reaction pressure of the carbonation reactor in which the 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 in the carbonation reactor to 40 to 120°C and injecting carbon dioxide and ammonia to produce sodium bicarbonate (NaHCO3) may be performed. If 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.

[0033] 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.

[0034] When carbon dioxide is injected as a gas, the reaction time can vary depending on whether aeration is used. With aeration, reaction times of less than 4 hours may be possible. However, the optimal pressure and reaction time may vary depending on the size, space, and conditions of the reactor.

[0035] The chemical formula of sodium bicarbonate is NaHCO3, and in solution, it contains bicarbonate ions (HCO3 -) increases, the production of sodium bicarbonate also 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 above sodium bicarbonate, the pH of the solution may become 7.5 or lower. In this case, the bicarbonate ion (HCO3 - ) is converted to carbonic acid (H2CO3), which reduces the rate of sodium bicarbonate production. Therefore, it is preferable to first add ammonia to the sodium sulfate solution before adding carbon dioxide to sufficiently dissolve it before adding carbon dioxide.

[0036] The 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.

[0037] Meanwhile, the recovery rate of sodium bicarbonate can be adjusted by adjusting the mass ratio of the sodium sulfate-containing material and the water as the eluent. That is, the recovery rate of sodium bicarbonate recovered is 50% (Na +In order to obtain the above (based on mole) mass ratio of the sodium sulfate-containing material and the eluent, the mass ratio 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 sodium recovery rate, and if the water ratio is too high, exceeding the above range, the sodium recovery rate 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 as the amount of water increases, the amount of undissolved desulfurization waste decreases.

[0038] Meanwhile, Na + To recover 50 mol% of sodium bicarbonate based on molar concentration, ammonia (NH3) / sodium (Na) in the waste solution + ) is preferably 0.8 to 1.3. 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.

[0039] The present invention includes 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.

[0040] The step of controlling the particle size of the above-mentioned sodium bicarbonate may be performed in a particle size reactor (300), and at this time, the temperature of the particle size reactor (300) may be performed at a temperature 5 to 40°C lower than the step of producing sodium bicarbonate (NaHCO3), 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.

[0041] Meanwhile, the temperature of the step of controlling the particle size of the above-mentioned medium 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.

[0042] For example, the produced sodium bicarbonate can be produced by controlling the temperature using a particle sizer reactor, for example, a rotary circulation reactor, and then producing a coarse-grained sodium bicarbonate (301). The step of adjusting the particle size of the sodium bicarbonate may be such that the particle size of the sodium bicarbonate is adjusted to 40 to 250 μm, and preferably 50 to 200 μm. If the particle size of the sodium bicarbonate is less than 40 μm, handling is difficult due to flying, and there is a problem that it is difficult to control the input amount of the sodium bicarbonate in a process that uses the sodium bicarbonate as a raw material.

[0043] 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 may be slow, making it difficult to control the particle size. If the cooling rate exceeds the above range, crystals are formed quickly, causing problems in controlling the particle size distribution. 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.

[0044] In the step of producing sodium bicarbonate (NaHCO3) 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 the sodium bicarbonate may be lower than that of the sodium bicarbonate produced with pure sodium sulfate. Therefore, an additional sodium bicarbonate washing step may be 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 may be improved.

[0045] At this time, washing can be performed with 0.5 to 4 parts by weight of water per 1 part by weight of 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.

[0046] Furthermore, 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 decompose back into sodium carbonate, and therefore, the drying of the sodium bicarbonate is preferably performed at a temperature of 50°C or lower.

[0047] However, if the final target product is sodium carbonate rather than sodium bicarbonate, the resulting sodium bicarbonate can be dried at temperatures above 50°C to obtain sodium carbonate. Furthermore, the solution used for washing to improve the purity of the sodium bicarbonate can be recycled as a dissolving agent.

[0048] 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 filtrate to produce gypsum (402), and this step may be performed in a gypsum reactor (400). More specifically, the filtrate obtained after the carbonation reaction contains sulfate ions (SO4 2- ) is contained in large quantities, a calcium-containing substance can be added to manufacture the sulfate ions contained in the filtrate into gypsum.

[0049] 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 (CaCl2), wollastonite, limestone, olivine, serpentine, asbestos, and deinking ash.

[0050] When a calcium-containing substance is added to the filtrate whose pH is optimized to be between 7.5 and 9.0 to produce the above-mentioned sodium bicarbonate, the pH of the filtrate rises to 9 or more. When the pH of the filtrate becomes 9 or more, the carbon dioxide remaining in the solution is converted to carbonate ions (CO3 2- ) exists in the form of calcium ions (Ca 2+ ) reacts with carbonate ions to produce calcium carbonate (CaCO3). In addition, carbon dioxide remaining in the solution at high pH levels produces hydroxyl radicals (OH) in the water. - ) to form slaked lime (Ca(OH)2).

[0051] 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, the wastewater produced after the carbonation reaction contains a large amount of ammonia, so 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 must be 60°C and pH 8.0 or higher, respectively.

[0052] 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.

[0053] To increase the pH of the waste solution, a manufactured quicklime slurry can be injected, and it can also be injected in powder form rather than slurry form. The waste solution, once heated by the addition of the quicklime slurry, generates ammonia gas simply by stirring. However, methods such as solution injection can be applied to reduce the ammonia recovery rate and time. The ammonia gas generated in this way can be injected directly into the carbonation reactor or dissolved in water to produce ammonia water, which can then be injected into the carbonation reactor.

[0054] At this time, the molar ratio of calcium ions and sulfate ions (Ca 2+ : SO4 2- ) is preferably 1:1.0 to 1.3, and if the ratio of sulfate ions exceeds 1.3, the purity of 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.

[0055] The reaction between calcium-containing substances and water causes 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.

[0056] The recovered ammonia can be reused in the form of gas or remanufactured into ammonia water and reused.

[0057] 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 (CaCl2), wollastonite, limestone, olivine, serpentine, asbestos, and deinking ash.

[0058] 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.

[0059] According to another embodiment of the present invention, a device that can be used to produce sodium bicarbonate and gypsum according to the present invention described above is provided. Figure 6 schematically illustrates an exemplary reactor for producing sodium bicarbonate according to the present invention.

[0060] 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 using 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 (NaHCO3) 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.

[0061] In the above 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 (NaHCO3) by 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, through a circulating reactor.

[0062] Furthermore, the reactor for producing sodium bicarbonate of the present invention may further include an ammonia recovery reactor in which a calcium-containing substance 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 produced through evaporation and concentration.

[0063] At this time, each reaction occurring in each reactor is as described above.

[0064] Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely illustrative examples to aid understanding of the present invention and are not intended to limit the scope of the present invention.

[0065] Example

[0066] Example 1: Preparation of sodium bicarbonate

[0067] 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 the sodium leached solution was recovered.

[0068] Next, to synthesize sodium bicarbonate, 75 mL of sodium sulphate 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.

[0069] Upon completion of the reaction, sodium bicarbonate is produced as a white solid precipitate, which is then filtered for solid-liquid separation. The sodium bicarbonate thus obtained is dried at room temperature. If sodium bicarbonate is heated above 50°C during the carbonation reaction, it decomposes into sodium carbonate, increasing its purity and decreasing its yield.

[0070] 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 carried out at a pressure of 7 bar in 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.

[0071] The reaction results of 100 g of desulfurized waste are summarized in Table 1 below.

[0072] [Table 1]

[0073]

[0074] Example 2: Preparation of plaster

[0075] To determine the ammonia recovery rate in an ammonia recovery reactor after gypsum production, 100 mL of carbonated waste solution was placed in the reactor, heated to 80°C, and then 7 M CaO slurry was added. The reactor was then aerated with nitrogen.

[0076] 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.

[0077] Meanwhile, the amount of gypsum produced was measured according to the amount of CaO added during ammonia recovery after evaporation and concentration of the remaining residue after gypsum recovery. The concentration was performed by placing the waste solution after ammonia stripping into a reactor and evaporating and concentrating at 80°C. The mass of the final remaining solid was measured, and the resulting yield of gypsum (CaSO4) is shown in Figure 4.

[0078] In the graphs of Figures 3 and 4, the x-axis represents the volume of 7M quicklime (CaO) per 100 mL of the filtrate (waste liquid) generated after carbonation.

[0079] Experimental Example 1: Particle size of sodium bicarbonate according to reaction temperature

[0080] 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 sodium bicarbonate crystals and coarsen the particle size, and the temperature of the circulating sodium bicarbonate solution was controlled by cooling to 40 to 70°C, which is lower than the temperature at which sodium bicarbonate is generated in the carbonation reaction.

[0081] In more detail, the sodium bicarbonate solution was circulated in the carbonation reactor at temperatures of 40℃, 60℃, 80℃, and 100℃ for 60 minutes each, and after cooling to 40℃ in the circulating reactor, the sodium bicarbonate particle size was measured, and the results are shown in Fig. 5. The particle size reactor is composed of a cooling reactor and a room temperature reactor, and the sodium bicarbonate solution is introduced into the room temperature reactor and then circulated to the cooling reactor.

[0082] 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.

[0083] [Explanation of symbols]

[0084] 100: Dissolution reactor

[0085] 101: Dissolving agent 102: Sodium sulfate waste 103: Waste

[0086] 200: Carbonation reactor

[0087] 201: Carbon dioxide containing gas 202: Ammonia gas or solution

[0088] 300: Particle size reactor

[0089] 301: Medium

[0090] 400: Gypsum Reactor

[0091] 401: Calcium-containing substances 402: Gypsum

[0092] 500: Ammonia recovery reactor

[0093] 501: Balance

Claims

1. 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 (NaHCO3); 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:

2. A method for producing 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 5 to 40°C lower than that of the step of producing sodium bicarbonate (NaHCO3).

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.

4. A method for producing sodium bicarbonate in the first paragraph, wherein the pH of the sodium sulfate solution is 7.5 to 9.

0.

5. 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 ㎛.

6. A method for producing sodium bicarbonate, further comprising a 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.

7. A method for producing gypsum, wherein the method further comprises 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.

8. 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.

9. A method for producing gypsum, in accordance with 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.

10. A method for manufacturing gypsum in paragraph 7, wherein the calcium-containing material is quicklime (CaO).

11. A method for manufacturing gypsum, wherein in paragraph 10, the quicklime (CaO) is added in a volume of 10 to 50 mL per 100 mL of wastewater produced after a carbonation reaction.

12. A dissolution reactor that produces a sodium aqueous solution by dissolving sodium ions from a sodium sulfate-containing material using a dissolution 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 and sodium bicarbonate (NaHCO3) 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.

13. 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.

14. 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 accordance with paragraph 13.

Images