Manufacturing method and manufactuaring device of sodium bicarbonate and gypsum

Abstract

The present invention relates to a manufacturing method and manufacturing device of sodium bicarbonate and gypsum, comprising the steps of: injecting carbon dioxide (CO2) and ammonia (NH3) into a sodium sulfate solution to produce sodium bicarbonate; producing and recovering first gypsum (CaSO4) by injecting a calcium (Ca)-containing material into a first filtrate generated in the step of producing the sodium bicarbonate; adding sodium carbonate (Na2CO3 to a second filtrate generated in the step of manufacturing and recovering the first gypsum and precipitating the calcium carbonate (CaCO3), to thereby remove the Ca material and recover ammonia; and producing second gypsum having higher purity than the first gypsum by mixing the first gypsum with waste liquid generated in the step of recovering ammonia and then injecting sulfuric acid. According to the present invention, the issue of scale caused by calcium can be solved, and the costs of manufacturing sodium bicarbonate and gypsum can be reduced.

Description

Manufacturing method and manufacturing device for sodium bicarbonate and gypsum

[0001] The present invention relates to a method and apparatus for producing sodium bicarbonate and gypsum.

[0002] Sulfur oxides (SOx) are not only a major cause of acid rain, but are also a harmful gas that, when absorbed by the human body, can cause respiratory diseases. With the development of industry, the amount of SOx emitted from various factories, thermal power plants, and incinerators is increasing. To minimize these emissions, various desulfurization methods are being applied on-site.

[0003] Currently, sintering plants in steel mills use sodium bicarbonate (sodium hydrogen carbonate, NaHCO3) as an adsorbent to remove sulfur oxides, and the amount of sodium bicarbonate used is increasing every year to meet increasingly stringent environmental regulations.

[0004] Importing industrial sodium bicarbonate from overseas presents a significant challenge, as its import price fluctuates significantly depending on overseas economic conditions. Furthermore, the reaction using sodium bicarbonate to remove sulfur oxides produces carbon dioxide and sodium sulfate (Na2SO4), which are currently being landfilled, resulting in increased disposal costs and secondary environmental issues.

[0005] By following the process of manufacturing sodium bicarbonate and gypsum using sodium bicarbonate, various issues such as waste reduction, carbon neutrality, and stable supply of raw materials through internal circulation of sodium bicarbonate can be resolved, and therefore, the development of related technologies is urgently needed.

[0006] The method for manufacturing sodium bicarbonate and gypsum of the present invention removes calcium contained in the filtrate by adding sodium carbonate (Na2CO3) to precipitate calcium carbonate (CaCO3), thereby solving the problem of equipment scale caused by calcium, and calcium ions (Ca) in the filtrate 2+ ) to a level where operation is possible.

[0007] A method for producing sodium bicarbonate and gypsum according to one embodiment of the present invention comprises the steps of producing sodium bicarbonate by adding carbon dioxide (CO2) and ammonia (NH3) to a sodium sulfate solution; producing and recovering first gypsum (CaSO4) by adding a calcium (Ca)-containing material to a first filtrate generated in the step of producing the sodium bicarbonate; and producing and recovering first gypsum by adding sodium carbonate (Na2CO3) to a second filtrate generated in the step of producing and recovering the first gypsum to precipitate calcium carbonate (CaCO3), thereby producing calcium ions (Ca 2+ ) and then recovering ammonia; and a step of mixing the first gypsum with the waste liquid generated in the step of recovering ammonia and then adding sulfuric acid to produce second gypsum having a higher purity than the first gypsum.

[0008] The above sodium sulfate solution can be prepared through a step of forming a sodium sulfate solution from a raw material including sodium sulfate (Na2SO4).

[0009] The recovered ammonia can be reintroduced into the sodium sulfate solution in the step of manufacturing the sodium bicarbonate.

[0010] The second filtrate may contain 40 to 1000 ppm of calcium based on the total concentration of the second filtrate.

[0011] The above sodium carbonate can be added to the second filtrate in an amount of 0.1 to 10 wt% based on the total weight of the second filtrate.

[0012] The above calcium-containing material may be quicklime (CaO).

[0013] A method for producing sodium bicarbonate and gypsum according to another embodiment of the present invention may further include, after the step of producing the second gypsum, a step of removing a Ca substance by adding sodium carbonate (Na2CO3) to the fourth filtrate generated in the step of producing the second gypsum to precipitate calcium carbonate (CaCO3).

[0014] According to another embodiment of the present invention, a device for manufacturing sodium bicarbonate and gypsum comprises: a sodium bicarbonate manufacturing device that manufactures sodium bicarbonate by receiving a sodium sulfate solution, carbon dioxide (CO2), and ammonia (NH3); a first gypsum manufacturing device that manufactures first gypsum (CaSO4) by receiving a first filtrate and a calcium (Ca)-containing material generated from the sodium bicarbonate manufacturing device; and a second filtrate and sodium carbonate (Na2CO3) generated from the first gypsum manufacturing device to precipitate calcium carbonate (CaCO3), thereby producing calcium ions (Ca). 2+ ) and an ammonia recovery device for recovering ammonia; and a second gypsum production device for receiving and mixing waste liquid generated from the ammonia recovery device and the first gypsum, and then receiving sulfuric acid to produce second gypsum having a higher purity than the first gypsum.

[0015] According to the method for manufacturing sodium bicarbonate and gypsum of the present invention, the problem of scale caused by calcium can be solved.

[0016] In addition, according to the method for manufacturing sodium bicarbonate and gypsum of the present invention, the manufacturing cost of sodium bicarbonate and gypsum can be reduced.

[0017] Figure 1 is a flow chart schematically showing a method for manufacturing sodium bicarbonate and gypsum according to one embodiment of the present invention.

[0018] Figure 2(a) shows the XRD analysis results of a solid phase produced in a method for manufacturing sodium bicarbonate and gypsum according to one embodiment of the present invention.

[0019] Figure 2(b) shows the XRD analysis results of a solid produced in a method for manufacturing sodium bicarbonate and gypsum according to one embodiment of the present invention.

[0020] Hereinafter, preferred embodiments of the present invention will be described with reference to various examples. 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.

[0021] One aspect of the present invention relates to a method for manufacturing sodium bicarbonate and gypsum.

[0022] The flue gas from the steel mill sintering plant contains sulfur oxides (SOx), and the reaction equation for removing sulfur oxides (SOx) with sodium bicarbonate (sodium hydrogen carbonate, NaHCO3) is as follows: Equation 1.

[0023] [Formula 1]

[0024] 2NaHCO3(s) + SO2(g) + 1 / 2O2(g) → Na2SO4(s) + 2CO2(g) + H2O (g)

[0025] As shown in Equation 1, the desulfurization process using sodium bicarbonate emits carbon dioxide. Furthermore, the reaction using sodium bicarbonate to remove sulfur oxides produces sodium sulfate (sodium sulfate, Na2SO4). Since sodium bicarbonate is composed of sodium and sulfate, sodium can be produced from sodium bicarbonate, and sulfate can be produced from gypsum (CaSO4).

[0026] When sodium bicarbonate is dissolved in water and reacted with carbon dioxide and ammonia, baking soda is produced, and when a calcium-containing substance is added to the wastewater produced, gypsum can be produced.

[0027] The desulfurization waste generated from the sintering plant of a steel mill contains calcium (Ca). Specifically, the sintering waste generated from the sintering plant contains about 3% by weight of calcium. The sodium bicarbonate production facility removes calcium ions (Ca) present in the filtrate. 2+ ), scale is generated on the wall of the equipment, which interferes with normal operation. Therefore, in order to improve the efficiency of process operation, calcium ions (Ca) in the solution are added before the filtrate is introduced into the equipment. 2+ ) concentration must be reduced. In particular, in the wastewater treatment process through ammonia recovery and evaporation concentration, the calcium ion (Ca) in the filtrate must be reduced before being fed into the facility. 2+ ) The concentration must be lowered to 120 ppm or less to ensure smooth operation.

[0028] Calcium ion solubility (g / 100 mL H2O) in the form of calcium chloride (CaCl2), calcium sulfate (CaSO4), and calcium carbonate (CaCO3) as a function of temperature is shown in Table 1.

[0029] Substance 20 ℃ 40 ℃ 60 ℃ 80 ℃ Calcium chloride (CaCl2) 74.5 128 137 147 Calcium sulfate (CaSO4) 0.25 50.26 50.24 40.234 Calcium carbonate (CaCO3) 6.17 x 10 -4 ---

[0030] As can be seen in Table 1, calcium ions (Ca 2+ ) has low solubility in the form of calcium carbonate (CaCO3), making it easy to precipitate. Therefore, carbonate ions (CO3 2- ) and a substance with high solubility is added to Ca 2+ (aq.)+ CO3 2- (aq.) a CaCO3(s) reaction can be induced.

[0031] Figure 1 is a schematic diagram illustrating a hydrogen production device according to one embodiment of the present invention. The present invention will now be described in more detail with reference to Figure 1.

[0032] The method for producing sodium bicarbonate and gypsum of the present invention comprises the steps of producing sodium bicarbonate by adding carbon dioxide (CO2) and ammonia to a sodium sulfate solution; producing and recovering first gypsum (CaSO4) by adding a calcium (Ca)-containing material to the first filtrate generated in the step of producing sodium bicarbonate; and producing and recovering first gypsum by adding sodium carbonate (Na2CO3) to the second filtrate generated in the step of producing and recovering first gypsum to precipitate calcium carbonate (CaCO3), thereby producing calcium ions (Ca 2+ ) and then recovering ammonia; and a step of mixing the first gypsum into the waste liquid generated in the step of recovering ammonia and then adding sulfuric acid to produce second gypsum.

[0033] According to the method for manufacturing sodium bicarbonate and gypsum of the present invention, calcium ions (Ca 2+ ) can be reduced to a level where operation is possible. Therefore, the cost of manufacturing sodium bicarbonate and gypsum can be reduced through stable operation.

[0034] The method for producing sodium bicarbonate and gypsum of the present invention includes a step of producing sodium bicarbonate by adding carbon dioxide (CO2) and ammonia to a sodium sulfate solution.

[0035] The above sodium sulfate solution can be prepared through a step of forming a sodium sulfate solution from a raw material containing sodium sulfate (Na2SO4).

[0036] The raw material containing sodium sulfate may be, for example, desulfurization waste. The raw material containing sodium sulfate may be dissolved in a dissolving agent and stirred to produce a mixture. The dissolving agent may be water. The mixture may be stirred and solid / liquid separated to obtain solid desulfurization waste (primary waste) and a sodium sulfate solution.

[0037] The above first gypsum is low-purity gypsum, and the above second gypsum is high-purity gypsum having a higher purity than the above first gypsum.

[0038] The method for producing sodium bicarbonate and gypsum of the present invention includes a step of producing sodium bicarbonate by adding carbon dioxide and ammonia to the sodium sulfate solution.

[0039] The method for producing sodium bicarbonate and gypsum of the present invention includes a step of producing and recovering first gypsum by adding a calcium-containing material to the first filtrate generated in the step of producing the sodium bicarbonate. The calcium-containing material may be quicklime (CaO).

[0040] The method for manufacturing sodium bicarbonate and gypsum of the present invention is to precipitate calcium carbonate (CaCO3) by adding sodium carbonate (Na2CO3) to the second filtrate generated in the step of manufacturing and recovering the first gypsum, thereby producing calcium ions (Ca 2+ ) and then recovering ammonia.

[0041] The method for producing sodium bicarbonate and gypsum of the present invention includes a step of mixing the first gypsum with the waste liquid generated in the step of recovering the ammonia, and then adding sulfuric acid to produce a second gypsum having a higher purity than the first gypsum.

[0042] Depending on the pH, the form in which calcium is formed varies. When the pH is lower than 6, calcium ions mainly exist in the form of calcium sulfate (CaSO4) or calcium chloride (CaCl2), and when the pH is higher than 6, they exist in the form of calcium carbonate (CaCO3). When the pH is higher than 12, they can also exist in the form of slaked lime (Ca(OH)2). Basically, the pH of desulfurization waste is 9, and after the production of sodium bicarbonate, the pH decreases to between 7 and 8. In order to recover ammonia, calcium-containing substances (CaO and Ca(OH)2, etc.) are added to increase the pH to 11 or higher, so CO3 2- When the containing material is added, the calcium carbonate (CaCO3) production reaction occurs well. Various CO3 2- Although the inclusions exist, the operating costs can be optimized in the sodium bicarbonate and gypsum production processes by using sodium carbonate (Na2CO3), which can be produced by heating the sodium bicarbonate within the process.

[0043] The method for producing sodium bicarbonate and gypsum according to the present invention can re-introduce the recovered ammonia into the sodium sulfate solution during the step of producing sodium bicarbonate. This prevents environmental pollution by recycling the ammonia rather than discarding it, and reduces the cost of producing sodium bicarbonate.

[0044] The second filtrate may contain about 40 to 1000 ppm of calcium based on the total concentration of the second filtrate.

[0045] The method for manufacturing sodium bicarbonate and gypsum of the present invention recovers gypsum from waste liquid and adds sodium carbonate (Na2CO3) to the remaining second filtrate in an amount of about 0.1 to 10 wt% based on the total weight of the second filtrate to precipitate calcium carbonate (CaCO3), thereby producing calcium ions (Ca 2+ ) can be removed.

[0046] The method for manufacturing sodium bicarbonate and gypsum of the present invention may further include, after the step of recovering ammonia, a step of recovering ammonia from the waste liquid and adding sulfuric acid (H2SO4) to the remaining filtrate to form and recover gypsum.

[0047] The method for manufacturing sodium bicarbonate and gypsum of the present invention is to precipitate calcium carbonate (CaCO3) by adding sodium carbonate (Na2CO3) to the fourth filtrate generated in the step of manufacturing the second gypsum, thereby producing calcium ions (Ca 2+ ) may further include a step of removing the .

[0048] The method for manufacturing sodium bicarbonate and gypsum of the present invention comprises the above calcium ion (Ca 2+ ) may further include a wastewater treatment step. Through the wastewater treatment step, wastewater from which secondary waste has been removed can be discharged.

[0049] Another aspect of the present invention relates to a device for manufacturing sodium bicarbonate and gypsum.

[0050] The apparatus for manufacturing sodium bicarbonate and gypsum of the present invention comprises: a sodium bicarbonate manufacturing machine that manufactures sodium bicarbonate by receiving a sodium sulfate solution, carbon dioxide (CO2), and ammonia (NH3); a first gypsum manufacturing machine that manufactures first gypsum (CaSO4) by receiving a first filtrate and a calcium (Ca)-containing material generated from the sodium bicarbonate manufacturing machine; and a second filtrate and sodium carbonate (Na2CO3) generated from the first gypsum manufacturing machine to precipitate calcium carbonate (CaCO3), thereby producing calcium ions (Ca). 2+) and an ammonia recovery device for recovering ammonia; and a second gypsum production device for receiving and mixing waste liquid generated from the ammonia recovery device and the first gypsum, and then receiving sulfuric acid to produce second gypsum having a higher purity than the first gypsum.

[0051] Example

[0052] Hereinafter, the present invention will be described in more detail with examples. The following examples are intended to further illustrate the present invention, but are not intended to limit the present invention.

[0053] Example 1

[0054] Steps for manufacturing a bicarbonate

[0055] A mixture was prepared by adding 100 g of desulfurized waste and 200 mL of water and stirring at 40°C for 1 hour. After stirring, the mixture was separated into solid and liquid to obtain solid desulfurized waste (primary waste) and sodium sulfate solution.

[0056] The preparation of sodium sulfate solution was repeated until 370 g of sodium sulfate solution was obtained.

[0057] To 370 g of the above-mentioned sodium sulfate solution produced, 70 g of an aqueous ammonia solution of 25 to 30 wt% and 48.5 g of carbon dioxide were added, and the mixture was reacted at a temperature of 40°C and a pressure of 7 bar for 4 hours to obtain a slurry in which sodium bicarbonate was produced. The slurry in which sodium bicarbonate was produced was subjected to solid / liquid separation to obtain a first filtrate and sodium bicarbonate.

[0058] Step 1: Manufacturing plaster

[0059] 250 g of 25 wt% quicklime (CaO) slurry was added to the first filtrate and stirred for 1 hour. After stirring, the solid / liquid was separated to produce and recover the second filtrate and the first gypsum.

[0060] Steps to recover ammonia

[0061] 0.5 g of sodium carbonate (Na2CO3) was added to 100 g of the recovered second filtrate, stirred at room temperature for 30 minutes, and then solid / liquid was separated to recover the third filtrate and the first solid phase.

[0062] The recovered third residue was heated to 80°C and aerated using an inert gas to recover ammonia (NH3) within the residue.

[0063] Step 2: Manufacturing plaster

[0064] After aeration, the waste liquid from which NH3 was removed was mixed with 100 g of the first gypsum, and 85 g of a 30 wt% sulfuric acid aqueous solution was slowly added and stirred for 1 hour to produce a slurry. After that, the slurry was separated into solids and liquids to recover the fourth filtrate and the second gypsum. 0.5 g of sodium carbonate (Na2CO3) was added to 100 g of the recovered fourth filtrate, stirred for 30 minutes at room temperature, and separated into solids and liquids to recover the fifth filtrate and the second solid phase.

[0065] After adding 90 g of 30 wt% hydrochloric acid aqueous solution to reduce the pH of the fifth filtrate to 6 or less, 0.5 g of sodium carbonate (Na2CO3) was added to 100 g of the recovered sixth filtrate and stirred at room temperature for 30 minutes. Calcium ions (Ca) of the sixth filtrate 2+ ) concentrations are shown in Table 4. Calcium ion (Ca 2+ ) The concentration analysis method is the same as the measurement method of the third filtrate above.

[0066] Examples 2 to 5

[0067] Sodium bicarbonate and gypsum were manufactured in the same manner as in Example 1, except that 1, 3, 5, and 10 g of sodium carbonate (Na2CO3) were added, respectively.

[0068] Comparative Example 1

[0069] Baking soda and gypsum were manufactured in the same manner as in Example 1, except that sodium carbonate (Na2CO3) was not added.

[0070] Experimental example

[0071] Calcium ions (Ca) of the third filtrate of Examples 1 to 5 and Comparative Example 1 2+ ) concentration changes are shown in Table 2. Calcium ion (Ca 2+ ) Concentration measurement was performed using the IC (Ion Chromatography) method.

[0072] The results of XRD analysis of the first solid phase of Examples 1 to 5 and Comparative Example 1 are shown in Fig. 2(a). It can be confirmed that when sodium carbonate (Na2CO3) is added in excess, unreacted Na2CO3 and other impurities, rather than CaCO3, are mixed into the solid phase.

[0073] Na2CO3 input amount (g)Ca 2+ Concentration (ppm) Comparative Example 10430 Example 10.5200 Example 21150 Example 33100 Example 4590 Example 51080

[0074] Calcium ions (Ca) of the recovered fifth filtrate of Examples 1 to 5 and Comparative Example 1 2+ ) The results of XRD analysis of the concentration change and recovered second solid phase are shown in Table 3 and Fig. 2(b). Calcium ion (Ca 2+ ) The concentration analysis method is the same as the measurement method of the third filtrate and the first solid phase.

[0075] Na2CO3 input amount (g)Ca 2+ Concentration (ppm) Comparative Example 10310 Example 10.5180 Example 21120 Example 3390 Example 4590 Example 51090

[0076] Tables 2 and 3 show that as the amount of sodium carbonate (Na2CO3) added increased, calcium ions (Ca) in the third and sixth filtrates 2+ ) concentration can be confirmed to decrease. Calcium ion (Ca) of the 6th filtrate of Examples 1 to 5 and Comparative Example 1 2+ ) concentrations are shown in Table 4.

[0077] Na2CO3 input amount (g)Ca2+ Concentration (ppm) Comparative Example 10340 Example 10.5330 Example 21350 Example 33360 Example 45340 Example 510320

[0078] As a result of the analysis in Table 4, the pH was low and calcium ions (Ca) in the seventh filtrate 2+ ) can be confirmed that the concentration does not decrease.

[0079] 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.

Claims

1. A step for producing sodium bicarbonate by adding carbon dioxide (CO2) and ammonia (NH3) to a sodium sulfate solution; A step of manufacturing and recovering first gypsum (CaSO4) by adding a calcium (Ca)-containing material to the first filtrate generated in the step of manufacturing the above-mentioned sodium bicarbonate; Calcium carbonate (CaCO3) is precipitated by adding sodium carbonate (Na2CO3) to the second filtrate generated in the step of manufacturing and recovering the first gypsum, thereby producing calcium ions (Ca 2+ ) and then recovering ammonia; and A method for producing sodium bicarbonate and gypsum, comprising a step of mixing the first gypsum with the waste liquid generated in the step of recovering the ammonia and then adding sulfuric acid to produce second gypsum having a higher purity than the first gypsum.

2. In paragraph 1, The above sodium sulfate solution is a method for producing baking soda and gypsum, wherein the sodium sulfate solution is produced through a step of forming a sodium sulfate solution from a raw material containing sodium sulfate (Na2SO4).

3. In paragraph 1, A method for producing sodium bicarbonate and gypsum, wherein the recovered ammonia is reintroduced into the sodium sulfate solution in the step of producing the sodium bicarbonate.

4. In paragraph 1, A method for producing baking soda and gypsum, wherein the second residue contains 40 to 1000 ppm of calcium based on the total concentration of the second residue.

5. In paragraph 1, A method for producing baking soda and gypsum, wherein the sodium carbonate is added to the second filtrate in an amount of 0.1 to 10 wt% based on the total weight of the second filtrate.

6. In paragraph 1, The above calcium-containing material is quicklime (CaO), a method for manufacturing baking soda and gypsum.

7. In paragraph 1, After the second step of making plaster, A method for manufacturing baking soda and gypsum, further comprising a step of removing Ca material by adding sodium carbonate (Na2CO3) to the fourth filtrate generated in the step of manufacturing the second gypsum to precipitate calcium carbonate (CaCO3).

8. A sodium bicarbonate manufacturing machine that manufactures sodium bicarbonate by supplying sodium sulfate solution, carbon dioxide (CO2), and ammonia (NH3); A first gypsum manufacturing machine that manufactures first gypsum (CaSO4) by receiving the first filtrate and calcium (Ca)-containing material generated from the above-mentioned double-glazed manufacturing machine; The second filtrate and sodium carbonate (Na2CO3) produced in the first gypsum manufacturing machine are supplied to precipitate calcium carbonate (CaCO3), thereby producing calcium ions (Ca 2+ ) to recover ammonia; and A device for manufacturing sodium bicarbonate and gypsum, including a second gypsum manufacturing device that receives and mixes waste liquid generated from the ammonia recovery device and the first gypsum, and then supplies sulfuric acid to manufacture second gypsum having a higher purity than the first gypsum.

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