Method for producing inorganic compounds using desulfurized gypsum for reducing greenhouse gas emissions

Abstract

The present invention relates to a method for producing an inorganic compound using desulfurized gypsum for reducing greenhouse gas emissions, and more particularly, to a method for producing anhydrous gypsum and calcium carbonate, which are used for various applications such as construction materials, using desulfurized gypsum, which is an industrial waste as a circulative resource, and an eluent as raw materials, and the eluent can be reused after separation, thereby significantly reducing greenhouse gas emissions and process costs compared to conventional processes.

Description

[Technical Field]

[0001] The present invention relates to a method for producing an inorganic compound using desulfurized gypsum for reducing greenhouse gas emissions. More specifically, the present invention relates to a method for producing an inorganic compound using desulfurized gypsum, which is an industrial waste as a recyclable resource, and an eluent as raw materials to produce anhydrous gypsum and calcium carbonate, which are used for various purposes such as construction materials, and the eluent can be reused after separation, thereby significantly reducing greenhouse gas emissions and process costs compared to conventional processes. [Background technology]

[0002] Domestic greenhouse gas emissions averaged 606.2 million tons of CO2eq. annually from 2007 to 2017, with energy and industrial processes accounting for over 94% of this. Of these, carbon dioxide has a global warming potential (GWP) of 1, which is lower than other greenhouse gases, but the amount of carbon dioxide emitted reached 604 million tons of CO2eq., accounting for over 91% of total emissions, and having a significant impact on global warming. Furthermore, emissions in 2017 increased by 23% compared to 2007, and the problem has become more serious over time.

[0003] Precipitated calcium carbonate (hard calcium carbonate, PCC, CaCO3) is used as an additive and filler to improve quality in the fields of food, paper, rubber, plastics, paint, etc. The conventional PCC manufacturing technology involves using mined limestone to remove carbon dioxide at high temperatures, then reacting it with carbon dioxide again to produce limestone, and the following reaction takes place: 1st.CaCO3 (limestone) → CaO (lime) + CO2 (≧900℃) 2nd. CaO + H2O → Ca(OH)2 3rd.Ca(OH)2+CO2→CaCO3(PCC)+H2O

[0004] However, this conventional method requires a heat source to convert limestone into quicklime, which increases the process cost. In addition, greenhouse gases such as carbon dioxide that are generated when the heat source and limestone dissociate have a negative impact on the environment.

[0005] Anhydrous gypsum (calcium sulfate, CaSO4) is also used as a typical construction material. However, since there are no mines capable of extracting anhydrous gypsum in Korea, most of the amount is imported from overseas.

[0006] Therefore, there remains a need for a method for producing anhydrous gypsum and calcium carbonate, which are used in various industrial materials, while reducing greenhouse gas emissions and process costs. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a method for producing inorganic compounds, which can produce anhydrous gypsum and calcium carbonate, which are used for various applications such as construction materials, using desulfurized gypsum and an eluate, which are industrial waste, as raw materials, and which can reuse the eluate after separation, thereby significantly reducing greenhouse gas emissions and process costs compared to conventional processes. [Means for solving the problem]

[0008] In order to achieve the above-mentioned technical objectives, the present invention provides a method for producing an inorganic compound using desulfurized gypsum, which includes: an anhydrous gypsum powder production step of filtering a mixture of desulfurized gypsum, an eluent, and water to separate the filtrate and an anhydrous gypsum cake, and drying the separated anhydrous gypsum cake; and a calcium carbonate powder production step of supplying a carbon dioxide-containing gas to the filtrate separated in the anhydrous gypsum powder production step, filtering the filtrate to separate it into a calcium carbonate cake and an eluent, and drying the separated calcium carbonate cake; wherein the eluent separated in the calcium carbonate powder production step is supplied to the anhydrous gypsum powder production step and reused. [Effects of the Invention]

[0009] According to the method for producing an inorganic compound using desulfurized gypsum of the present invention, the amount of limestone used, a natural resource, can be reduced and resources can be conserved because the method uses desulfurized gypsum, a circulative resource generated in an FBC boiler, as a raw material. Moreover, since the process for converting limestone into quicklime, as in existing calcium carbonate production methods, is unnecessary, it is possible to reduce the cost of heat sources and greenhouse gases such as carbon dioxide generated in the quicklime production process, which is environmentally friendly.

[0010] In addition, it will be possible to manufacture high-value-added light calcium carbonate and anhydrous gypsum using desulfurized gypsum, which is undervalued as a recyclable resource, and this will enable domestic production of anhydrous gypsum, which is highly dependent on imports. Furthermore, the CaO separated from desulfurized gypsum will react with carbon dioxide, greatly contributing to reducing greenhouse gas emissions. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating a process of Example 1, which is a method for producing an inorganic compound of the present invention. [Figure 2] 1 is a diagram schematically illustrating a process of a comparative example of the present invention corresponding to the prior art; [Figure 3] FIG. 1 is a diagram showing the results of X-ray diffraction analysis of the anhydrous gypsum powders obtained in Examples 1 and 2. [Figure 4] FIG. 1 shows the results of X-ray diffraction analysis confirming that vaterite-form PCC was obtained in Examples 1 and 2. [Figure 5] FIG. 1 is a diagram showing the results of X-ray diffraction analysis of inorganic compounds (anhydrous gypsum powder and PCC) obtained in a comparative example. [Figure 6] FIG. 1 is a diagram showing the results of SEM analysis of the PCC obtained in Example 1. [Figure 7] FIG. 1 is a diagram showing the results of SEM analysis of PCC obtained in a comparative example. BEST MODE FOR CARRYING OUT THE INVENTION

[0012] The present disclosure will be described in detail below. The method for producing an inorganic compound using desulfurized gypsum of the present invention includes: an anhydrous gypsum powder production step of filtering a mixture of desulfurized gypsum, an eluent, and water to separate the filtrate and an anhydrous gypsum cake, and drying the separated anhydrous gypsum cake; and a calcium carbonate powder production step of supplying a carbon dioxide-containing gas to the filtrate separated in the anhydrous gypsum powder production step, filtering the filtrate to separate it into a calcium carbonate cake and an eluent, and drying the separated calcium carbonate cake, wherein the eluent separated in the calcium carbonate production step is supplied to the anhydrous gypsum production step for reuse.

[0013] In this specification, the anhydrous gypsum powder production step may be referred to as the first step, and the calcium carbonate powder production step may be referred to as the second step.

[0014] The method for producing an inorganic compound using desulfurized gypsum of the present invention includes a step of producing an anhydrous gypsum powder by filtering a mixture of desulfurized gypsum, an eluent, and water to separate it into a filtrate and an anhydrous gypsum cake, and drying the separated anhydrous gypsum cake.

[0015] The CaO (CaO·CaSO4) in the desulfurized gypsum dissolves by hydration and separates from CaSO4, but the degree of dissolution is low, so an eluent that can promote dissolution is injected. As the eluent, various components described below can be used, and in one embodiment, NH4Cl can be used. The reaction at this time is as follows: CaSO4·CaO(s)+2NH4Cl(aq)→CaSO4(s)+CaCl2(aq)+2NH3(aq)+H2O(l)

[0016] In one embodiment of the present invention, CaSO(s), CaCl(aq), 2NH(aq), and HO(l) may be present in the mixture of desulfurized gypsum, eluent, and water due to the reaction. The CaCl has a higher solubility in water than Ca(OH) produced when no separate eluent is added (i.e., when only desulfurized gypsum and water are mixed), and therefore CaO can be eluted and separated from the anhydrous gypsum with a small amount of water.

[0017] The desulfurization gypsum used in the present invention is produced for the purpose of removing sulfur oxides generated in a circulating fluidized bed boiler (CFBC boiler), and its raw material is limestone. The desulfurization reaction pathway in a CFBC boiler is as follows: 1st.CaCO3→CaO+CO2(850~900℃) 2nd. CaO + SO2 + 1 / 2O2 → CaSO4

[0018] The desulfurized gypsum (CaO·CaSO4) used in the present invention may contain 40 to 60% by weight of CaSO4 and 25 to 45% by weight of CaO. In the desulfurization reaction of the second step, the CaO conversion rate is about 50%, and precipitated calcium carbonate is produced using the unreacted CaO present in the desulfurized gypsum, and the other components can be used as an anhydrous gypsum product.

[0019] The eluent used in the anhydrous gypsum powder production process may be selected from the group consisting of NH4Cl, sodium boride, urea, NH4NO3, and combinations thereof, for example, NH4Cl.

[0020] In the anhydrous gypsum powder production process, the weight ratio of desulfurized gypsum to water may be 1:5 to 1:45, for example, 1:5 to 1:40, 1:6 to 1:30, or 1:8 to 1:20. If the content of water relative to the desulfurized gypsum is less than this ratio, the amount of CaO dissolved in the desulfurized gypsum is small, which may result in a decrease in the quality (purity) of the anhydrous gypsum and a decrease in the amount of calcium carbonate produced. Conversely, if the water content is more than this ratio, it is difficult to obtain additional effects.

[0021] In the anhydrous gypsum powder production process, the weight ratio of the desulfurized gypsum to the eluent may be 1:0.7 to 1:2, for example, 1:0.75 to 1:1.8 or 1:0.8 to 1:1.5. If the content of the eluent relative to the desulfurized gypsum is less than this ratio, the amount of CaO dissolved in the desulfurized gypsum is small, which may result in a decrease in the quality (purity) of the anhydrous gypsum and the production amount of calcium carbonate. Conversely, if the content of the eluent is more than this ratio, it is difficult to obtain additional effects.

[0022] In the anhydrous gypsum powder production process, the separated anhydrous gypsum cake can be dried to produce anhydrous gypsum powder. The produced anhydrous gypsum can be used as a building material, fertilizer, etc. after washing and drying processes.

[0023] The anhydrous gypsum powder production process can be carried out at 20° C. to 30° C., for example, at room temperature, for 2 to 10 hours, for example, 2 to 8 hours or 2 to 6 hours.

[0024] The method for producing an inorganic compound using desulfurized gypsum of the present invention includes a calcium carbonate powder production step of supplying a carbon dioxide-containing gas to the filtrate separated in the anhydrous gypsum powder production step, filtering the filtrate to separate it into a calcium carbonate cake and an eluate, and drying the separated calcium carbonate cake.

[0025] The filtrate separated in the anhydrous gypsum powder manufacturing process may contain CaCl and NH due to a reaction between CaO separated from the desulfurized gypsum and the eluate. In one embodiment, a carbon dioxide-containing gas is supplied to the filtrate from which CaO has been eluted (calcium is eluted in the form of CaCl), and when carbon dioxide is added, CaCl precipitates as CaCO (PCC), and NH (aq.) and Cl precipitate. - combine to form NH4Cl. CaCl2(aq)+2NH3(aq)+2H2O(l)+CO2(g)→CaCO3(s)+2NH4Cl(aq)+H2O(l)

[0026] In the calcium carbonate powder production process, the mixture can be separated into a calcium carbonate cake and an eluate, and the separated eluate can be reused by being supplied to the anhydrous gypsum production process. In one embodiment, the eluate may be NHCl, and can be used to elute CaO in the desulfurized gypsum by being supplied again to the anhydrous gypsum powder production process, thereby reducing the process cost due to the use of the eluate.

[0027] The carbon dioxide-containing gas used in the calcium carbonate powder production process is not particularly limited, but for example, exhaust gas from a circulating fluidized bed combustion boiler or 100% carbon dioxide gas can be used. Although not particularly limited, the supply rate of the carbon dioxide-containing gas can be 100 to 500 mL / min.

[0028] In the calcium carbonate powder manufacturing process, the calcium carbonate cake and the eluent are separated, and then the eluent is supplied to the anhydrous gypsum manufacturing process, where the separated calcium carbonate cake is dried to produce calcium carbonate powder. The produced calcium carbonate becomes precipitated calcium carbonate (PCC), which, unlike limestone, has high whiteness and small particle size, and is used in various industries as a functional material.

[0029] The calcium carbonate powder production process can be carried out at 20° C. to 30° C., for example, at room temperature, for 1 to 5 hours, for example, 1 to 4 hours or 1 to 3 hours.

[0030] The present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited thereto.

[0031] Example Example 1, Example 2 and Comparative Example The method for producing an inorganic compound using desulfurized gypsum of the present invention was carried out in the configuration shown in Table 1 below. (First step: anhydrous gypsum powder production step, second step: calcium carbonate powder production step)

[0032] In Example 1, an eluent was used for the first time, in Example 2, an eluent separated from the reaction of the second step of Example 1 was used, and in the comparative example, only desulfurized gypsum and water were used without using a separate eluent.

[0033] The steps of Example 1, which is a method for producing an inorganic compound according to the present invention, and the steps of a comparative example are shown schematically in FIGS. 1 and 2, respectively.

[0034] [Table 1]

[0035] The results of X-ray diffraction analysis of the inorganic compounds obtained in Examples 1 and 2, namely anhydrous gypsum powder and calcium carbonate (PCC), are shown in Figures 3 and 4, respectively.

[0036] 3, it was confirmed that the anhydrous gypsum after the first step in Example 1 was produced in a form in which CaO and Ca(OH)2 components had been removed, compared to the raw material desulfurized gypsum. Furthermore, in Example 2, it was confirmed that the reused eluent eluted the CaO and Ca(OH)2 components in the raw material desulfurized gypsum, as in Example 1. This can also be said to prove the effectiveness of reusing the eluent in the method of producing an inorganic compound using desulfurized gypsum of the present invention.

[0037] 4 shows the results of X-ray diffraction analysis, which confirmed that vaterite-type calcium carbonate (PCC) was obtained in Examples 1 and 2. Vaterite-type PCC was synthesized by adding carbon dioxide to the filtrate in the second step of Example 1, and it was confirmed that PCC of the same type (vaterite) as in Example 1 was synthesized in Example 2, in which the eluent of Example 1 was reused for treatment. This can also be said to prove the effectiveness of reusing the eluent in the method for producing an inorganic compound using desulfurized gypsum of the present invention.

[0038] On the other hand, the results of X-ray diffraction analysis of the inorganic compounds (anhydrous gypsum powder and PCC) obtained in the comparative example are shown in Figure 5. In the comparative example, a larger amount of water (solvent) was used in the first step compared to the examples, and sufficient reaction time was allowed to dissolve CaO in the desulfurized gypsum, but it was confirmed that CaO remained in a hydrated state in the anhydrous gypsum. Furthermore, it was confirmed that PCC in a calcite form, different from that in the examples, was synthesized in the second step.

[0039] Figure 6 shows the SEM analysis results of the PCC obtained in Example 1, and Figure 7 shows the SEM analysis results of the PCC obtained in the Comparative Example. It was confirmed that the PCC obtained in Example 1 was vaterite particles, and the PCC obtained in the Comparative Example was calcite particles. As can be seen from Figure 6, vaterite particles are spherical, unlike calcite particles, and when used as a rubber additive, they have the advantage of increasing the strength of rubber while maintaining its flexibility, thereby improving economic efficiency, etc. On the other hand, as can be seen from Figure 7, calcite particles are mainly hexagonal in shape and have corners, making them less flexible than vaterite particles.

Claims

1. A method for producing an inorganic compound using desulfurized gypsum, A process for producing anhydrous gypsum powder, which comprises filtering a mixture of desulfurized gypsum, an eluent and water to separate the filtrate and anhydrous gypsum cake, and drying the separated anhydrous gypsum cake; and A calcium carbonate powder production step of supplying a carbon dioxide-containing gas to the filtrate separated in the anhydrous gypsum powder production step, filtering the filtrate to separate it into a calcium carbonate cake and an eluate, and drying the separated calcium carbonate cake; The eluate separated in the calcium carbonate powder production process is supplied to the anhydrous gypsum powder production process for reuse, The desulfurized gypsum is desulfurized gypsum containing quicklime (CaO.CaSO 4 ), The anhydrous gypsum is anhydrous gypsum (CaSO 4 ) that does not contain quicklime, A method for producing an inorganic compound using desulfurized gypsum, wherein the eluent is selected from the group consisting of NH 4 Cl, NH 4 NO 3 and a combination thereof.

2. The desulfurized gypsum is produced in a CFBC boiler; 40 to 60% by weight of CaSO 4 The method for producing an inorganic compound using the desulfurized gypsum according to claim 1, wherein the desulfurized gypsum contains 25 to 45% by weight of CaO.

3. The method for producing an inorganic compound using desulfurized gypsum according to claim 1, wherein in the anhydrous gypsum powder production step, a weight ratio of desulfurized gypsum to water is 1:5 to 1:

45.

4. The method for producing an inorganic compound using desulfurized gypsum according to claim 1, wherein in the anhydrous gypsum powder production step, a weight ratio of desulfurized gypsum to eluent is 1:0.7 to 1:

2.

5. The method for producing an inorganic compound using desulfurized gypsum according to claim 1, wherein the carbon dioxide-containing gas is an exhaust gas from a circulating fluidized bed combustion boiler.

6. The method for producing an inorganic compound using desulfurized gypsum according to claim 1, wherein the anhydrous gypsum powder production step is carried out at 20 ° C. to 30 ° C. for 2 to 10 hours.

7. The method for producing an inorganic compound using desulfurized gypsum according to claim 1, wherein the calcium carbonate powder production step is carried out at 20°C to 30°C for 1 to 5 hours.

8. A process for producing desulfurized gypsum (CaO.CaSO 4 ) containing quicklime through a desulfurization reaction between sulfur oxides in exhaust gas from a CFBC boiler and limestone; A step of adding ammonium chloride (NH 4 Cl) and water to the desulfurized gypsum (CaO·CaSO 4 ) containing quicklime, filtering the resulting mixture, and separating the filtrate from anhydrous gypsum (CaSO 4 ); and supplying the desulfurized exhaust gas as a carbon dioxide-containing gas to the filtrate to remove carbon dioxide from the desulfurized exhaust gas and produce calcium carbonate (CaCO 3 ); A method for producing an inorganic compound using desulfurized gypsum for reducing greenhouse gas emissions, comprising:

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