TW201838917A - Method for separating calcium sulfate and calcium carbonate from desulfurized gypsum waste generated in flue gas desulfurization process with which the purities of the separated calcium sulfate and calcium carbonate are 90% and 100%, respectively - Google Patents
Method for separating calcium sulfate and calcium carbonate from desulfurized gypsum waste generated in flue gas desulfurization process with which the purities of the separated calcium sulfate and calcium carbonate are 90% and 100%, respectively Download PDFInfo
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- calcium sulfate
- flue gas
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- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 title claims abstract description 114
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 title claims abstract description 102
- 229910000019 calcium carbonate Inorganic materials 0.000 title claims abstract description 54
- 239000002699 waste material Substances 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 32
- 230000023556 desulfurization Effects 0.000 title claims abstract description 32
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 21
- 239000003546 flue gas Substances 0.000 title claims abstract description 21
- 239000010440 gypsum Substances 0.000 title claims abstract description 19
- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 19
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 47
- 239000000725 suspension Substances 0.000 claims abstract description 35
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 23
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 23
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000000292 calcium oxide Substances 0.000 claims abstract description 16
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 235000010216 calcium carbonate Nutrition 0.000 claims description 55
- NKWPZUCBCARRDP-UHFFFAOYSA-L calcium bicarbonate Chemical compound [Ca+2].OC([O-])=O.OC([O-])=O NKWPZUCBCARRDP-UHFFFAOYSA-L 0.000 claims description 17
- 229910000020 calcium bicarbonate Inorganic materials 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 14
- 239000002244 precipitate Substances 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 8
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910044991 metal oxide Inorganic materials 0.000 claims description 6
- 150000004706 metal oxides Chemical class 0.000 claims description 6
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 3
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 2
- 239000011777 magnesium Substances 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 208000004434 Calcinosis Diseases 0.000 claims 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims 1
- FYHXNYLLNIKZMR-UHFFFAOYSA-N calcium;carbonic acid Chemical compound [Ca].OC(O)=O FYHXNYLLNIKZMR-UHFFFAOYSA-N 0.000 claims 1
- 230000003647 oxidation Effects 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 claims 1
- 239000006227 byproduct Substances 0.000 abstract description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 abstract description 6
- 235000011941 Tilia x europaea Nutrition 0.000 abstract description 6
- 239000004571 lime Substances 0.000 abstract description 6
- 238000002156 mixing Methods 0.000 abstract description 5
- 238000010298 pulverizing process Methods 0.000 abstract description 4
- 235000011132 calcium sulphate Nutrition 0.000 description 32
- 235000012255 calcium oxide Nutrition 0.000 description 11
- 238000000926 separation method Methods 0.000 description 11
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 239000011575 calcium Substances 0.000 description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 5
- 229910052791 calcium Inorganic materials 0.000 description 5
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 5
- 239000002006 petroleum coke Substances 0.000 description 5
- 235000019738 Limestone Nutrition 0.000 description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 239000000920 calcium hydroxide Substances 0.000 description 4
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 4
- 239000006028 limestone Substances 0.000 description 4
- 239000000395 magnesium oxide Substances 0.000 description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 229910052717 sulfur Inorganic materials 0.000 description 4
- 239000011593 sulfur Substances 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 239000001175 calcium sulphate Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 150000007530 organic bases Chemical class 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 229910052815 sulfur oxide Inorganic materials 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 150000004763 sulfides Chemical class 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/20—Waste processing or separation
Landscapes
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
Description
本發明有關於一種分離方法，特別是指一種能夠有效地自排煙脫硫製程中所產生之含有氧化鈣、碳酸鈣與硫酸鈣的脫硫石膏廢棄物(或稱副產石灰)中分離出硫酸鈣與碳酸鈣的方法。 The invention relates to a separation method, in particular to a desulfurization gypsum waste (or by-product lime) containing calcium oxide, calcium carbonate and calcium sulfate which can be effectively produced in the process of flue gas desulfurization and desulfurization. A method of calcium sulfate and calcium carbonate.
石油焦(petroleum coke)是煉油廠所產生的副產物，含硫量較高(約高於6%)的石油焦一般都用來作為水泥廠或是發電廠的燃料。然而，含硫量高的石油焦在燃燒時會排放出超過標準量的硫氧化物，因此，為了使燃燒石油焦時排放出的煙氣符合環保法規，一般係使用排煙脫硫處理程序除去煙氣中諸如一氧化硫(SO)、二氧化硫(SO2)等硫化物。前述排煙脫硫處理程序可區分為燃燒前脫硫、燃燒中脫硫和燃燒後脫硫等三種。若按脫硫劑的種類區分，可進一步區分為以下五種方法：以碳酸鈣(CaCO3，石灰石)為基礎的鈣基法、以氧化鎂(MgO)為基礎的鎂基法、以亞硫酸鈉(Na2SO3)為基礎的鈉基法、以氨(NH3)為基礎的氨基法、以及以有機鹼為基礎的有機鹼法。前揭處理程序中較普遍使用的商業化技術為鈣基法，所佔比例高於90%。 Petroleum coke is a by-product of refineries, and petroleum coke with a high sulfur content (about 6% higher) is generally used as a fuel for cement plants or power plants. However, petroleum coke with high sulfur content will emit more than the standard amount of sulfur oxides when burning. Therefore, in order to make the flue gas emitted when burning petroleum coke comply with environmental regulations, it is generally removed by using a flue gas desulfurization treatment program. Sulfur in the flue gas such as sulfur monoxide (SO) and sulfur dioxide (SO 2 ). The foregoing process for desulfurization of flue gas can be divided into three types: desulfurization before combustion, desulfurization in combustion, and desulfurization after combustion. According to the type of desulfurizer, it can be further divided into the following five methods: calcium-based method based on calcium carbonate (CaCO 3 , limestone), magnesium-based method based on magnesium oxide (MgO), sodium sulfite ( Na 2 SO 3 )-based sodium-based method, ammonia (NH 3 )-based amino method, and organic base-based organic base method. The more commonly used commercial technology in the pre-extraction process is the calcium-based method, which accounts for more than 90%.
詳言之，排煙脫硫處理程序主要是使用石灰石(CaCO3)、氧化鈣(CaO，生石灰)或氫氧化鈣(Ca(OH)2)等作為硫化物吸收劑，與煙氣中的一氧化硫或二氧化硫等硫化物進行化學反應，從而除去煙氣中的硫化物。舉例來說，由於石灰石以及含硫的石油焦經過約850℃~900℃高溫燃燒後會分別產生多孔性的生石灰(CaO)以及二氧化硫，透過生石灰會與空氣中的氧以及前述二氧化硫反應而生成硫酸鈣(CaSO4)，據以達成脫硫的目的。 In detail, the flue gas desulfurization treatment program mainly uses limestone (CaCO 3 ), calcium oxide (CaO, quicklime) or calcium hydroxide (Ca(OH) 2 ) as a sulfide absorbent, and one of the flue gas. Sulfur compounds such as sulfur oxides or sulfur dioxide are chemically reacted to remove sulfides in the flue gas. For example, since limestone and sulfur-containing petroleum coke are burned at a high temperature of about 850 ° C to 900 ° C, porous quicklime (CaO) and sulfur dioxide are separately generated, and the quicklime reacts with oxygen in the air and the aforementioned sulfur dioxide to form sulfuric acid. Calcium (CaSO 4 ) is used to achieve the purpose of desulfurization.
但是，逐漸堆積於生石灰之孔洞內的硫酸鈣將導致脫硫效率降低，為了維持脫硫效率，就必須不斷地添加石灰石，如此反覆的結果，最終產生大量主要成分為硫酸鈣以及氧化鈣與碳酸鈣混合物的脫硫石膏廢棄物，一般稱為「副產石灰」。 However, calcium sulphate gradually accumulated in the pores of the quicklime will cause the desulfurization efficiency to decrease. In order to maintain the desulfurization efficiency, limestone must be continuously added. As a result, a large amount of the main components are calcium sulphate and calcium oxide and carbonic acid. The desulfurized gypsum waste of the calcium mixture is generally referred to as "by-product lime".
然而，由於前述副產石灰(脫硫石膏)的用途受限，致使其儼然成為廢棄物而衍生環保問題，因此，亟需發展出使前述副產石灰(脫硫石膏)能夠被有效再利用的方法。 However, since the use of the aforementioned by-product lime (desulfurization gypsum) is limited, which causes it to become a waste and is environmentally-friendly, it is urgent to develop the by-product lime (desulfurization gypsum) to be effectively reused. method.
有鑑於此，本發明之主要目的在於提供一種能夠自排煙脫硫處理程序中所產生之脫硫石膏廢棄物(副產石灰)中分離出硫酸鈣與碳酸鈣的方法，藉以使前述廢棄物能夠被有效再利用。 In view of the above, the main object of the present invention is to provide a method for separating calcium sulfate and calcium carbonate from desulfurized gypsum waste (by-product lime) generated in a flue gas desulfurization treatment program, thereby making the foregoing waste Can be effectively reused.
為達成前述目的，本發明所提供的分離方法主要包括有下列步驟：a)將該廢棄物粉碎並與水混合成一pH值為8.0~12.0的懸浮液；b)使步驟a)之懸浮液與二氧化碳反應，直至該懸浮液之pH值為7.0~9.0；c)使步驟b)之懸浮液再次與二氧化碳反應，直至該懸浮液之pH值為5.5~6.0，靜置一段 時間使該懸浮液分離成硫酸鈣沉澱物及碳酸氫鈣澄清液；d)收集步驟c)之該硫酸鈣沉澱物，並加熱步驟c)之該碳酸氫鈣澄清液以排出二氧化碳；以及e)靜置步驟d)中加熱後之該碳酸氫鈣澄清液一段時間，以獲得碳酸鈣沉澱物。 In order to achieve the above object, the separation method provided by the present invention mainly comprises the following steps: a) pulverizing the waste and mixing with water to form a suspension having a pH of 8.0 to 12.0; b) reacting the suspension of step a) with Carbon dioxide reaction until the pH of the suspension is 7.0-9.0; c) reacting the suspension of step b) with carbon dioxide again until the pH of the suspension is 5.5-6.0, leaving it to stand for a period of time to separate the suspension Calcium sulfate precipitate and calcium bicarbonate clear liquid; d) collecting the calcium sulfate precipitate of step c), and heating the calcium bicarbonate clear liquid of step c) to discharge carbon dioxide; and e) standing in step d) The heated calcium bicarbonate clear solution is heated for a period of time to obtain a calcium carbonate precipitate.
透過本發明之分離方法，能夠成功地從脫硫處理程序後所產生之廢棄物中分離出高純度的碳酸鈣以及硫酸鈣(純度100%的碳酸鈣以及純度將近90%的硫酸鈣)，俾能夠有效的再利用分離出的碳酸鈣以及硫酸鈣，例如分離出的碳酸鈣能夠再應用於脫硫處理，以降低脫硫處理程序之成本；而分離出的硫酸鈣則能夠應用於建築材料、防火材料等。 Through the separation method of the present invention, high-purity calcium carbonate and calcium sulfate (calcium carbonate having a purity of 100% and calcium sulfate having a purity of nearly 90%) can be successfully separated from the waste generated after the desulfurization treatment process. The separated calcium carbonate and calcium sulfate can be effectively reused, for example, the separated calcium carbonate can be reused in the desulfurization treatment to reduce the cost of the desulfurization treatment process; and the separated calcium sulfate can be applied to building materials, Fireproof materials, etc.
在本發明所提供的分離方法中，該廢棄物包含有58.2%~76.3%之氧化鈣與碳酸鈣的混合物，以及23.5%~39.5%的硫酸鈣。更且，該廢棄物還包含有1.1%~2.3%的金屬氧化物。前述金屬氧化物為氧化矽、氧化鐵、氧化鎂、氧化鋁或前述之混合物。 In the separation method provided by the present invention, the waste contains 58.2% to 76.3% of a mixture of calcium oxide and calcium carbonate, and 23.5% to 39.5% of calcium sulfate. Moreover, the waste further contains 1.1% to 2.3% of metal oxide. The aforementioned metal oxide is cerium oxide, iron oxide, magnesium oxide, aluminum oxide or a mixture of the foregoing.
依據本發明所提供的分離方法，於步驟a)中，該廢棄物係被粉碎為具有等於或小於2mm之粒徑的顆粒。更且，粉碎之該廢棄物與水的混合重量比最好大於12，藉以更有效地分離出碳酸鈣。 According to the separation method provided by the present invention, in the step a), the waste is pulverized into particles having a particle diameter equal to or smaller than 2 mm. Further, it is preferable that the mixed weight ratio of the pulverized waste to water is more than 12, whereby calcium carbonate is more effectively separated.
在本發明所提供的分離方法中，步驟c)的靜置時間最好為至少30分鐘，使硫酸鈣沉澱物能夠充分地沉澱出來。此外，步驟e)的靜置時間最好為至少30分鐘，使碳酸鈣沉澱物能夠充分地沉澱出來。 In the separation method provided by the present invention, the standing time of the step c) is preferably at least 30 minutes to allow the calcium sulfate precipitate to be sufficiently precipitated. Further, the standing time of the step e) is preferably at least 30 minutes to allow the calcium carbonate precipitate to be sufficiently precipitated.
依據本發明所提供的分離方法，於步驟d)中，步驟c)之該碳酸氫鈣澄清液的加熱溫度為至少60℃，藉以分解出碳酸鈣及二氧化碳。前述分解出的二氧化碳能夠進一步被收集以提供步驟b)及/或步驟c)使用，俾令本發明之分離方法更具有低成本的附加優勢。 According to the separation method provided by the present invention, in the step d), the calcium hydrogencarbonate clarification liquid of the step c) is heated at a temperature of at least 60 ° C, thereby decomposing calcium carbonate and carbon dioxide. The aforementioned decomposed carbon dioxide can be further collected to provide the use of step b) and/or step c) to provide the additional advantages of the separation process of the present invention at a lower cost.
有關本發明所提供之自排煙脫硫製程中所產生之脫硫石膏廢棄物中分離出硫酸鈣與碳酸鈣的方法的技術特徵更詳細地說明於後。 The technical features of the method for separating calcium sulfate and calcium carbonate from the desulfurized gypsum waste produced in the self-exhaust gas desulfurization process provided by the present invention are explained in more detail later.
依據本發明所提供之自排煙脫硫製程中所產生之脫硫石膏廢棄物中分離出硫酸鈣與碳酸鈣的方法，主要包含有下列步驟：a)將該廢棄物粉碎並與水混合成一懸浮液，該懸浮液之pH值為8.0~12.0；b)使步驟a)之懸浮液與二氧化碳反應，直至該懸浮液之pH值為7.0~9.0；c)使步驟b)之懸浮液再次與二氧化碳反應，直至該懸浮液之pH值為5.5~6.0，靜置一段時間使該懸浮液分離成硫酸鈣沉澱物及碳酸氫鈣澄清液；d)收集步驟c)之該硫酸鈣沉澱物，並加熱步驟c)之該碳酸氫鈣澄清液以排出二氧化碳；以及e)靜置步驟d)中加熱後之該碳酸氫鈣澄清液一段時間，以獲得碳酸鈣沉澱物。 The method for separating calcium sulfate and calcium carbonate from the desulfurized gypsum waste produced in the self-exhaust smoke desulfurization process provided by the present invention mainly comprises the following steps: a) crushing the waste and mixing it with water Suspension, the pH of the suspension is 8.0 to 12.0; b) reacting the suspension of step a) with carbon dioxide until the pH of the suspension is 7.0 to 9.0; c) re-sending the suspension of step b) The carbon dioxide is reacted until the pH of the suspension is 5.5 to 6.0, and the suspension is allowed to stand for a period of time to separate the suspension into a calcium sulfate precipitate and a calcium hydrogencarbonate clear liquid; d) collecting the calcium sulfate precipitate of the step c), and The calcium bicarbonate clearing liquid of step c) is heated to discharge carbon dioxide; and e) the calcium hydrogencarbonate clearing liquid heated in step d) is allowed to stand for a period of time to obtain a calcium carbonate precipitate.
在本發明的分離方法中，該廢棄物主要包含有硫酸鈣(CaSO4)、碳酸鈣(CaCO3)以及氧化鈣(CaO)等成分。依據本發明之實施例，該廢棄物可包含有(但不限於)58.2%~76.3%之氧化鈣與碳酸鈣的混合物，以及23.5%~39.5%的硫酸鈣。除此之外，該廢棄物還可包含有(但不限於)1.1%~2.3%的金屬氧化物，例如氧化矽、氧化鐵、氧化鎂、氧化鋁或前述之混合物。 In the separation method of the present invention, the waste mainly contains components such as calcium sulfate (CaSO 4 ), calcium carbonate (CaCO 3 ), and calcium oxide (CaO). According to an embodiment of the invention, the waste may comprise, but is not limited to, 58.2% to 76.3% of a mixture of calcium oxide and calcium carbonate, and 23.5% to 39.5% calcium sulfate. In addition, the waste may contain, but is not limited to, 1.1% to 2.3% of a metal oxide such as cerium oxide, iron oxide, magnesium oxide, aluminum oxide or a mixture thereof.
於步驟a)中，係將廢棄物粉碎成具有等於或小於2mm粒徑的顆粒。粉碎該廢棄物的方式並無特定限制，例如可使用均質機或是本技術領域中常用於粉碎的其他裝置使廢棄物破碎，之後再以10mesh(2mm)的標準篩網進行過篩，以獲得粒徑等於或小於2mm的顆粒。依據本發明一實施例，將粉碎後的廢棄物置入反應槽中並與水混合，廢棄物與水的混合重量比最好大於12，俾令廢棄物中的氧化鈣能夠充分與水反應進而生成氫氧化鈣，藉以更有效地自廢棄物中分離出碳酸鈣，此時，懸浮液的pH值最好為8.0~12.0。需補充說明的是，前述反應槽可選擇地配備有用於攪拌的裝置，藉以使粉碎的廢棄物能夠均勻地分散於水中，形成懸浮液。 In the step a), the waste is pulverized into particles having a particle diameter equal to or smaller than 2 mm. There is no particular limitation on the manner in which the waste is pulverized. For example, the homogenizer or other means commonly used in the art for pulverization may be used to break the waste, and then sieved with a standard sieve of 10 mesh (2 mm) to obtain Particles having a particle diameter of 2 mm or less. According to an embodiment of the present invention, the pulverized waste is placed in a reaction tank and mixed with water, and the mixing ratio of waste to water is preferably greater than 12, so that the calcium oxide in the waste can fully react with water to generate Calcium hydroxide, in order to more effectively separate calcium carbonate from the waste, at this time, the pH of the suspension is preferably 8.0 ~ 12.0. It should be noted that the aforementioned reaction tank may be optionally equipped with a device for stirring, so that the pulverized waste can be uniformly dispersed in water to form a suspension.
於步驟b)中，係可將前述反應槽暴露於大氣中，使步驟a)之懸浮液中的氫氧化鈣能夠與大氣中的二氧化碳進行反應而生成碳酸鈣。此時，懸浮液的pH值最好為7.0~9.0。若pH值未位於此範圍內，則表示懸浮液中的氫氧化鈣未完全地轉換為碳酸鈣，如此，將使得最後分離出之碳酸鈣的量減少，同時使得最後分離出之硫酸鈣的純度降低。若pH值位於此範圍內，則表示懸浮液中的氫氧化鈣幾乎都已完全地轉換為碳酸鈣，亦即懸浮液的主要成分已由氧化鈣、碳酸鈣以及硫酸鈣轉換為碳酸鈣以及硫酸鈣。 In step b), the reaction vessel can be exposed to the atmosphere such that the calcium hydroxide in the suspension of step a) reacts with carbon dioxide in the atmosphere to form calcium carbonate. At this time, the pH of the suspension is preferably from 7.0 to 9.0. If the pH is not within this range, it means that the calcium hydroxide in the suspension is not completely converted to calcium carbonate, so that the amount of calcium carbonate finally separated is reduced, and the purity of the finally separated calcium sulfate is made. reduce. If the pH is within this range, it means that almost all of the calcium hydroxide in the suspension has been completely converted into calcium carbonate, that is, the main component of the suspension has been converted from calcium oxide, calcium carbonate and calcium sulfate to calcium carbonate and sulfuric acid. calcium.
於步驟c)中，可利用本領域常用的各種二氧化碳供給裝置，將大量的二氧化碳導入反應槽中，使懸浮液中的碳酸鈣與水以及二氧化碳進行反應，生成易溶於水的碳酸氫鈣(Ca(HCO3)2)。此時，懸浮液的pH值最好為5.5~6.0。若pH值未位於此範圍內，則表示懸浮液中的碳酸鈣未完全地轉換為碳酸氫鈣，如此，將使得最後分離出之碳酸鈣的量減少，同時使得最後 分離出之硫酸鈣的純度降低。之後，停止供應二氧化碳，並靜置至少30分鐘，使懸浮液分離成硫酸鈣沉澱物以及碳酸氫鈣澄清液。 In the step c), a large amount of carbon dioxide can be introduced into the reaction tank by using various carbon dioxide supply devices commonly used in the art, and the calcium carbonate in the suspension is reacted with water and carbon dioxide to form calcium bicarbonate which is easily soluble in water ( Ca(HCO 3 ) 2 ). At this time, the pH of the suspension is preferably 5.5 to 6.0. If the pH is not within this range, it means that the calcium carbonate in the suspension is not completely converted to calcium bicarbonate, so that the amount of calcium carbonate finally separated is reduced, and the purity of the finally separated calcium sulfate is made. reduce. Thereafter, the supply of carbon dioxide was stopped and allowed to stand for at least 30 minutes to separate the suspension into a calcium sulfate precipitate and a calcium hydrogencarbonate clear liquid.
於步驟d)中，將前述碳酸氫鈣澄清液移至一加熱槽中，並收集前述反應槽中的硫酸鈣沉澱物，獲得分離出的硫酸鈣。之後，加熱前述碳酸氫鈣澄清液到至少60℃，以降低碳酸氫鈣澄清液中之二氧化碳的溶解度，繼而排出二氧化碳。排出的二氧化碳能夠進一步收集並提供至步驟b)及/或步驟c)使用，如此更能有效地達降低本發明之分離方法的成本。於步驟e)中，停止加熱並靜置該碳酸氫鈣澄清液至少30分鐘，使碳酸鈣沉澱於加熱槽的底部，獲得分離出的碳酸鈣。 In the step d), the calcium bicarbonate clear liquid is transferred to a heating tank, and the calcium sulfate precipitate in the reaction tank is collected to obtain the separated calcium sulfate. Thereafter, the aforementioned calcium bicarbonate clearing liquid is heated to at least 60 ° C to reduce the solubility of carbon dioxide in the calcium bicarbonate clearing liquid, and then the carbon dioxide is discharged. The vented carbon dioxide can be further collected and supplied to step b) and/or step c), which is more effective in reducing the cost of the separation process of the present invention. In the step e), the heating is stopped and the calcium hydrogencarbonate clear liquid is allowed to stand for at least 30 minutes to precipitate the calcium carbonate at the bottom of the heating tank to obtain the separated calcium carbonate.
依據本發明前揭實施例之方法，進行實驗例1~2以及比較例1的實驗。各實驗例及比較例之廢棄物的組成成分顯示於下表1，實驗條件則顯示於下表2。需特別說明的是，比較例1於步驟c)中僅將二氧化碳導入反應槽中數秒，以維持其pH值為7。 Experiments of Experimental Examples 1 and 2 and Comparative Example 1 were carried out in accordance with the method of the first embodiment of the present invention. The composition of the waste of each of the experimental examples and the comparative examples is shown in Table 1 below, and the experimental conditions are shown in Table 2 below. Specifically, in Comparative Example 1, only carbon dioxide was introduced into the reaction tank for several seconds in step c) to maintain its pH value of 7.
按前揭實驗例1~2以及比較例1分離出的硫酸鈣與碳酸鈣分別進行脫水乾燥處理，之後分別秤重，並以下示式1及式2計算硫酸鈣純度與碳酸鈣的回收率，結果顯示於下表3。 Calcium sulfate and calcium carbonate separated according to the first experimental examples 1 and 2 and the comparative example 1 were subjected to dehydration drying treatment, respectively, and then weighed separately, and the purity of calcium sulfate and the recovery rate of calcium carbonate were calculated by the following formulas 1 and 2, The results are shown in Table 3 below.
上式1中，理論硫酸鈣重量=(表1廢棄物組成成分中硫酸鈣之平均含量)×(廢棄物總重量)。實驗例1~2及比較例1之廢棄物總重量為100克。 In the above formula 1, the theoretical calcium sulfate weight = (the average content of calcium sulfate in the waste constituents of Table 1) × (total waste weight). The total waste weight of Experimental Examples 1 to 2 and Comparative Example 1 was 100 g.
上式2中，理論碳酸鈣重量=(表1廢棄物組成成分中碳酸鈣之平均含量)×(廢棄物總重量)。實驗例1~2及比較例1之廢棄物總重量為100克。 In the above formula 2, the theoretical calcium carbonate weight = (the average content of calcium carbonate in the waste constituents of Table 1) × (total waste weight). The total waste weight of Experimental Examples 1 to 2 and Comparative Example 1 was 100 g.
由表3的結果可以清楚看出，依據本發明之方法的實施例1~2分離出之硫酸鈣的純度均高於90%，但比較例1分離出之硫酸鈣的純度僅56%。此外，本發明實施例1~2的碳酸鈣回收率均高於90%，而比較例1的碳酸鈣回收率不到60%，顯見本發明之分離方法不僅能夠有效地自廢棄物中分離出高純度的硫酸鈣，還能夠有效地提高碳酸鈣的回收率。 As is clear from the results of Table 3, the purity of the calcium sulfate separated in Examples 1 to 2 according to the method of the present invention was higher than 90%, but the purity of the calcium sulfate separated in Comparative Example 1 was only 56%. In addition, the calcium carbonate recovery rates of the first to second embodiments of the present invention are both higher than 90%, and the calcium carbonate recovery rate of the comparative example 1 is less than 60%. It is apparent that the separation method of the present invention can be effectively separated not only from the waste. High-purity calcium sulfate can also effectively increase the recovery rate of calcium carbonate.
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| CN113461034A (en) * | 2021-08-04 | 2021-10-01 | 中南大学 | Method for producing sodium sulfite from desulfurized gypsum |
| CN114057215A (en) * | 2021-11-17 | 2022-02-18 | 郑州大学 | Method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum |
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| CN111547755A (en) * | 2020-05-13 | 2020-08-18 | 广东奥胜新材料有限公司 | Preparation method and equipment of casting gypsum capable of being recycled |
| CN113461034A (en) * | 2021-08-04 | 2021-10-01 | 中南大学 | Method for producing sodium sulfite from desulfurized gypsum |
| CN113461034B (en) * | 2021-08-04 | 2022-07-22 | 中南大学 | Method for producing sodium sulfite from desulfurized gypsum |
| CN114057215A (en) * | 2021-11-17 | 2022-02-18 | 郑州大学 | Method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum |
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