CN114057215A - Method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum - Google Patents
Method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum Download PDFInfo
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- CN114057215A CN114057215A CN202111361714.1A CN202111361714A CN114057215A CN 114057215 A CN114057215 A CN 114057215A CN 202111361714 A CN202111361714 A CN 202111361714A CN 114057215 A CN114057215 A CN 114057215A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/468—Purification of calcium sulfates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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Abstract
The invention discloses a method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum. Firstly, roasting desulfurized gypsum and removing moisture to obtain roasted clinker; soaking the obtained roasted clinker in water, and performing solid-liquid separation after water soaking to obtain filtrate A and filter cake B; adding the obtained filter cake B into a washing tank for washing, then carrying out solid-liquid separation to obtain a filtrate C and a filter cake D, and returning the obtained filtrate C to the water leaching procedure in the step B for recycling; drying the obtained filter cake D to obtain a calcium sulfate product; introducing roasting flue gas generated in the roasting process into the obtained filtrate A for reaction to generate calcium carbonate precipitate, and performing solid-liquid separation on the obtained reactant; the calcium carbonate obtained by separation is returned to the desulfurization procedure for recycling, and the obtained filtrate is returned to the product washing tank for recycling. The method has the advantages of simple process, high comprehensive utilization rate and good economic benefit.
Description
The technical field is as follows:
the invention belongs to the technical field of bulk solid waste recycling, and particularly relates to a method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum.
Secondly, background art:
the desulfurized gypsum is a byproduct formed by adopting limestone-gypsum wet method or calcium hydroxide for desulfurizing sulfur-containing flue gas in the industries of coal-fired power, steel smelting, aluminum smelting, fluorine chemical industry, cement and the like, and the main component of the desulfurized gypsum (also called as flue gas desulfurized gypsum, sulfur gypsum or FGD gypsum) is CaSO4·2H2O, about 90-93%, and further about 3-8% of CaCO3About 1 to 5% of CaF2Mainly used asThe cement retarder can be used for manufacturing gypsum products, improving soil, roadbed backfill materials and the like. However, because the market of the desulfurized gypsum is seriously over-supplied, a great amount of desulfurized gypsum can not be effectively utilized every year, and the desulfurized gypsum must be stacked in an idle mode, so that a large amount of land resources are occupied. Particularly, the desulfurized gypsum containing hazardous impurities such as soluble fluoride belongs to dangerous solid waste, is easy to cause secondary pollution due to improper disposal, and causes potential pollution risk to local ecological environment. How to purify and carry out value-added utilization on the desulfurized gypsum, reduce the storage of the desulfurized gypsum and eliminate secondary pollution, and has profound research value and remarkable social and environmental benefits.
Patent application CN 113149055A discloses a method for preparing calcium carbonate and sulfate by using industrial desulfurized gypsum, which comprises the steps of carrying out size mixing treatment on desulfurized gypsum to obtain gypsum slurry, adjusting the gypsum slurry to be alkaline by adopting an alkaline compound (the alkaline compound is at least one of liquid ammonia, ammonia water, urea, sodium hydroxide and potassium hydroxide), introducing carbon dioxide gas for reaction, and carrying out solid-liquid separation after the reaction is finished to obtain a calcium carbonate product and a sulfate solution; after impurity removal treatment, concentrating and crystallizing the sulfate solution to obtain a sulfate product; the method can realize the resource comprehensive utilization of the desulfurized gypsum, can obtain a calcium carbonate product with higher purity, can return to the flue gas desulfurization process in the industries of electric power, fluorine chemical industry and metal smelting, can obtain byproducts such as sulfate (ammonium sulfate) and the like, can be used as fertilizers or industrial raw materials for agricultural production, and promotes the comprehensive utilization of sulfur and calcium resources.
The invention patent CN 113461034A discloses a method for producing sodium sulfite by using desulfurized gypsum, which uses desulfurized gypsum as raw material, uses sodium-containing solution (the sodium-containing solution is at least one of sodium bicarbonate, sodium carbonate and sodium hydroxide solution) as transformation solution, converts calcium sulfite in desulfurized gypsum into calcium bicarbonate, and simultaneously produces sodium sulfite as byproduct, thereby realizing that calcium in desulfurized gypsum is separated and recovered in the form of calcium bicarbonate or calcium carbonate, sulfur is separated and recovered in the form of sodium sulfite, changing waste into valuable, greatly reducing the subsequent environmental protection pressure of flue gas desulfurization, and being suitable for industrial application of desulfurized gypsum resource treatment.
Although the existing treatment method simply utilizes the desulfurized gypsum, the existing treatment method still has certain defects: the products are sodium sulfite, calcium carbonate, calcium bicarbonate and ammonium sulfate with lower added value, the investment is more, the output is less, and the enthusiasm of enterprises is not high.
Thirdly, the invention content:
the technical problem to be solved by the invention is as follows: aiming at the defects of the existing desulfurization gypsum treatment method, the invention provides a novel method for preparing high-purity calcium sulfate by using industrial desulfurization gypsum. The method has simple process, high comprehensive utilization rate and good economic benefit, realizes the value-added utilization of the desulfurized gypsum and the recycling of the calcium carbonate, and reduces the carbon dioxide emission in the production process; no additional medicament is needed, and no waste water, waste residue or waste gas is generated in the whole production process, so that the waste water, waste residue or waste gas reaches the standard and is discharged.
In order to solve the problems, the invention adopts the technical scheme that:
the invention provides a method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum, which comprises the following steps:
a. roasting the desulfurized gypsum to remove moisture, and decomposing calcium carbonate in the gypsum to generate calcium oxide and CO2Roasting to obtain roasted clinker;
b. b, performing water immersion on the roasted clinker obtained in the step a, and performing solid-liquid separation after the water immersion to obtain a filtrate A and a filter cake B, wherein the solute of the filtrate A is calcium hydroxide;
c. b, adding the filter cake B obtained in the step B into a washing tank for washing, then carrying out solid-liquid separation to obtain a filtrate C and a filter cake D, and returning the obtained filtrate C to the water leaching process in the step B for recycling; drying the obtained filter cake D to obtain a calcium sulfate product;
d. b, introducing roasting flue gas generated in the roasting process in the step a into the obtained filtrate A for reaction to generate calcium carbonate precipitate, and performing solid-liquid separation on the obtained suspension; the calcium carbonate obtained by separation is returned to the desulfurization procedure for recycling, and the obtained filtrate is returned to the product washing tank for recycling.
According to the method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum, in the step a, the mass percentage of the moisture in the desulfurized gypsum is 14-19%, and the mass percentage of the moisture in the roasted clinker after moisture removal is less than 0.5%.
According to the method for preparing high-purity calcium sulfate by using desulfurized gypsum, in the step a, the roasting temperature is 825-950 ℃ and the roasting time is 30-75 min.
According to the method for preparing high-purity calcium sulfate by using desulfurized gypsum, in the step a, the roasting temperature is 850-900 ℃ and the roasting time is 45-60 min.
According to the method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum, the desulfurized gypsum in the step a is desulfurized gypsum in any form obtained by treating industrial sulfur-containing flue gas.
According to the method for preparing high-purity calcium sulfate by using desulfurized gypsum, the liquid-solid ratio is controlled to be 2: 1-8: 1 in the water leaching process, and the stirring time is 45-120 min in the water leaching process.
According to the method for preparing high-purity calcium sulfate by using desulfurized gypsum, the liquid-solid ratio is controlled to be 5: 1-8: 1 in the water leaching process in the step b, and the stirring time is 60-90 min in the water leaching process.
According to the method for preparing high-purity calcium sulfate by using desulfurized gypsum, the liquid-solid ratio is controlled to be 2: 1-7: 1 in the washing process in the step c, and the stirring time is 30-120 min in the washing process.
According to the method for preparing high-purity calcium sulfate by using desulfurized gypsum, the liquid-solid ratio is controlled to be 5: 1-7: 1 in the washing process in the step c, and the stirring time is 60-90 min in the washing process.
According to the method for preparing high-purity calcium sulfate by using desulfurized gypsum, the reaction end point in the step d is that the pH value of the solution is 6.5-7.5, and the purity of the obtained calcium sulfate is more than or equal to 96%.
The invention relates to a method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum, which removes calcium carbonate in the gypsum by roasting and decomposing the calcium carbonate and then soaking and dissolving calcium oxide in water so as to achieve the aim of improving the purity of the gypsum, and the basic principle is as follows:
reaction taking place in step a: CaCO3→CaO+CO2
Reaction taking place in step b: CaO + H2O→Ca(OH)2
Reaction taking place in step d: ca (OH)2+CO2→CaCO3+H2O
The invention has the following positive beneficial effects:
1. the technical scheme of the invention properly utilizes the transformation of calcium carbonate, firstly, calcium carbonate is decomposed by roasting, then calcium oxide is dissolved by water immersion, and a gypsum and calcium hydroxide solution is obtained by solid-liquid separation, so that the calcium carbonate in the gypsum is effectively removed, the purity of the gypsum is obviously improved, and the content of calcium sulfate is improved from 90 percent to more than 96 percent, even more than 98 percent; and realizes calcium carbonate and CO2The carbon-saving effect is obvious by recycling in the system.
2. The whole operation process is green, no additional medicament is needed, no waste acid or waste alkali is involved, and no waste water or waste residue is discharged. Has the advantages of short process flow, low treatment cost, high comprehensive utilization rate, good economic benefit, convenient operation and the like, and is suitable for value-added utilization of various desulfurized gypsum.
In conclusion, the invention has obvious economic benefit and social benefit.
Fourthly, the specific implementation mode:
the invention is further illustrated by the following examples, which do not limit the scope of the invention.
The desulfurized gypsum adopted in the following examples is desulfurized gypsum in any form obtained by treating industrial sulfur-containing flue gas; the mass percentage of the water in the desulfurized gypsum is 14-19%, and after the water is removed, the mass percentage of the water in the obtained roasted clinker is less than 0.5%.
Example 1:
the invention discloses a method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum, which comprises the following detailed steps:
a. taking 1000 g of desulfurized gypsum (chemical of desulfurized gypsum) generated by flue gas desulfurization of coal-fired power plantComprises the following components: CaSO476.9％，H2O 14.5％，CaCO3 7.3％，CaF21.3 percent) of the powder is roasted, the roasting temperature is 850 ℃, and the roasting time is 60 min; removing water by roasting the desulfurized gypsum (in the roasting process, the contained calcium carbonate is completely decomposed to generate calcium oxide and CO2) 823 g of roasted clinker is obtained;
b. c, adding 823 g of the roasted clinker obtained in the step a into a leaching tank, then adding 4115 g of water, stirring and leaching for 90 min; after water leaching, carrying out solid-liquid separation to obtain 4156 g of filtrate A and 782 g of filter cake B;
c. adding the filter cake B obtained in the step B into a washing tank, adding 3910 g of water, stirring and washing for 90 min; then carrying out solid-liquid separation to obtain 3911 g of filtrate C and 781 g of filter cake D, and returning the obtained filtrate C to the water leaching procedure in the step b for recycling; drying the obtained filter cake D to obtain a calcium sulfate product, wherein the purity of the obtained calcium sulfate product is 98.46%;
d. b, introducing roasting flue gas generated in the roasting process in the step a into the obtained filtrate A (the filtrate A is calcium hydroxide solution) for reaction, wherein calcium hydroxide and carbon dioxide react to generate calcium carbonate precipitate in the reaction process, and the reaction is finished when the pH value of the reaction solution is 7.0; carrying out solid-liquid separation on the obtained reactant; the calcium carbonate obtained by separation is returned to the desulfurization procedure for recycling, and the obtained filtrate is returned to the product washing tank for recycling.
Example 2:
the invention discloses a method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum, which comprises the following detailed steps:
a. 1000 g of desulfurized gypsum (chemical composition of desulfurized gypsum: CaSO) produced by desulfurizing flue gas of electrolytic aluminum plant476.0％，H2O 14.0％，CaCO3 7.5％，CaF22.5 percent) of the powder is roasted, the roasting temperature is 900 ℃, and the roasting time is 30 min; removing water by roasting the desulfurized gypsum (in the roasting process, the contained calcium carbonate is completely decomposed to generate calcium oxide and CO2) Obtaining 827 grams of roasted clinker;
b. adding 827 grams of the roasted clinker obtained in the step a into a leaching tank, adding 4962 grams of water, stirring and leaching for 75 min; after water leaching, carrying out solid-liquid separation to obtain 5004 g of filtrate A and 785 g of filter cake B;
c. b, adding the filter cake B obtained in the step B into a washing tank, and then adding 4710 g of water to stir and wash for 75 min; then carrying out solid-liquid separation to obtain 4711 g of filtrate C and 784 g of filter cake D, and returning the obtained filtrate C to the water leaching procedure in the step b for recycling; drying the obtained filter cake D to obtain a calcium sulfate product, wherein the purity of the obtained calcium sulfate product is 96.94%;
d. b, introducing roasting flue gas generated in the roasting process in the step a into the obtained filtrate A (the filtrate A is calcium hydroxide solution) for reaction, wherein calcium hydroxide and carbon dioxide react to generate calcium carbonate precipitate in the reaction process, and the reaction is finished when the pH value of the reaction solution is 6.8; carrying out solid-liquid separation on the obtained reactant; the calcium carbonate obtained by separation is returned to the desulfurization procedure for recycling, and the obtained filtrate is returned to the product washing tank for recycling.
Example 3:
the invention discloses a method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum, which comprises the following detailed steps:
a. 1000 g of desulfurized gypsum (chemical composition of desulfurized gypsum: CaSO) generated by flue gas desulfurization in carbon plants for aluminum is taken477.3％，H2O 15.0％，CaCO3 4.7％，CaF23.1 percent) of the powder is roasted, the roasting temperature is 875 ℃, and the roasting time is 45 min; removing water by roasting the desulfurized gypsum (in the roasting process, the contained calcium carbonate is completely decomposed to generate calcium oxide and CO2) Obtaining 830 g of roasted clinker;
b. b, adding 830 g of the roasted clinker obtained in the step a into a leaching tank, and then adding 6640 g of water to stir for water leaching, wherein the stirring time is 45 min; after water leaching, carrying out solid-liquid separation to obtain 6666 g of filtrate A and 804 g of filter cake B;
c. b, adding the filter cake B obtained in the step B into a washing tank, and then adding 5628 g of water to stir and wash for 30 min; then, carrying out solid-liquid separation to obtain 5629 g of filtrate C and 803 g of filter cake D, and returning the obtained filtrate C to the water leaching procedure in the step b for recycling; drying the obtained filter cake D to obtain a calcium sulfate product, wherein the purity of the obtained calcium sulfate product is 96.26%;
d. b, introducing roasting flue gas generated in the roasting process in the step a into the obtained filtrate A (the filtrate A is calcium hydroxide solution) for reaction, wherein calcium hydroxide and carbon dioxide react to generate calcium carbonate precipitate in the reaction process, and the reaction is finished when the pH value of the reaction solution is 7.0; carrying out solid-liquid separation on the obtained reactant; the calcium carbonate obtained by separation is returned to the desulfurization procedure for recycling, and the obtained filtrate is returned to the product washing tank for recycling.
Claims (10)
1. A method for preparing high-purity calcium sulfate by utilizing desulfurized gypsum is characterized by comprising the following steps:
a. roasting the desulfurized gypsum to remove water, and decomposing calcium carbonate in the gypsum to generate calcium oxide and CO2Roasting to obtain roasted clinker;
b. b, performing water immersion on the roasted clinker obtained in the step a, and performing solid-liquid separation after the water immersion to obtain a filtrate A and a filter cake B;
c. b, adding the filter cake B obtained in the step B into a washing tank for washing, then carrying out solid-liquid separation to obtain a filtrate C and a filter cake D, and returning the obtained filtrate C to the water leaching process in the step B for recycling; drying the obtained filter cake D to obtain a calcium sulfate product;
d. b, introducing roasting flue gas generated in the roasting process in the step a into the obtained filtrate A for reaction to generate calcium carbonate precipitate, and performing solid-liquid separation on the obtained suspension; the calcium carbonate obtained by separation is returned to the desulfurization procedure for recycling, and the obtained filtrate is returned to the product washing tank for recycling.
2. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 1, wherein: in the step a, the mass percentage of the water in the desulfurized gypsum is 14-19%, and the mass percentage of the water in the roasted clinker obtained after the water is removed is less than 0.5%.
3. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 1, wherein: in the roasting process in the step a, the roasting temperature is 825-950 ℃, and the roasting time is 30-75 min.
4. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 3, wherein: in the roasting process in the step a, the roasting temperature is 850-900 ℃, and the roasting time is 45-60 min.
5. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 1, wherein: the desulfurization gypsum in the step a is desulfurization gypsum in any form obtained by treating industrial sulfur-containing flue gas.
6. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 1, wherein: and c, controlling the liquid-solid ratio to be 2: 1-8: 1 in the water leaching process, and stirring for 45-120 min in the water leaching process.
7. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 6, wherein: and c, controlling the liquid-solid ratio to be 5: 1-8: 1 in the water leaching process in the step b, and stirring for 60-90 min in the water leaching process.
8. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 1, wherein: and c, controlling the liquid-solid ratio to be 2: 1-7: 1 in the washing process, and stirring for 30-120 min in the washing process.
9. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 8, wherein: and c, controlling the liquid-solid ratio to be 5: 1-7: 1 in the washing process, and stirring for 60-90 min in the washing process.
10. The method for preparing high-purity calcium sulfate by using desulfurized gypsum according to claim 1, wherein: and d, the reaction end point in the step d is that the pH value of the solution is 6.5-7.5, and the purity of the obtained calcium sulfate is more than or equal to 96%.
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| DE3217394A1 (en) * | 1982-05-08 | 1983-11-10 | Saarbergwerke AG, 6600 Saarbrücken | Process for treating calcium sulphate from flue gas desulphurisation units |
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| US20140044619A1 (en) * | 2012-08-10 | 2014-02-13 | Sparstane Technologies LLC | Process for converting fgd gypsum to ammonium sulfate and calcium carbonate |
| CN104556184A (en) * | 2014-12-12 | 2015-04-29 | 安徽雪城超细碳酸钙有限公司 | Method for producing industrial precipitation-type nano calcium carbonate |
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| US20170369329A1 (en) * | 2015-01-14 | 2017-12-28 | Imerys Usa, Inc. | A process for converting natural calcium carbonate into precipitated calcium carbonate |
| TW201838917A (en) * | 2017-04-25 | 2018-11-01 | 洪瑞敏 | 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 |
| CN110817925A (en) * | 2019-10-23 | 2020-02-21 | 江苏沙钢集团有限公司 | Method for resource utilization of desulfurized fly ash |
| CN110917852A (en) * | 2019-11-21 | 2020-03-27 | 江苏省沙钢钢铁研究院有限公司 | Resource recovery method and resource recovery system for desulfurized fly ash |
| CN113149055A (en) * | 2021-05-27 | 2021-07-23 | 湖南西林环保材料有限公司 | Method for preparing calcium carbonate and sulfate by using industrial desulfurized gypsum |
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2021
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3217394A1 (en) * | 1982-05-08 | 1983-11-10 | Saarbergwerke AG, 6600 Saarbrücken | Process for treating calcium sulphate from flue gas desulphurisation units |
| CN101648723A (en) * | 2008-08-13 | 2010-02-17 | 徐铭 | Method for producing precipitated calcium carbonate |
| US20140044619A1 (en) * | 2012-08-10 | 2014-02-13 | Sparstane Technologies LLC | Process for converting fgd gypsum to ammonium sulfate and calcium carbonate |
| CN104556184A (en) * | 2014-12-12 | 2015-04-29 | 安徽雪城超细碳酸钙有限公司 | Method for producing industrial precipitation-type nano calcium carbonate |
| US20170369329A1 (en) * | 2015-01-14 | 2017-12-28 | Imerys Usa, Inc. | A process for converting natural calcium carbonate into precipitated calcium carbonate |
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| TW201838917A (en) * | 2017-04-25 | 2018-11-01 | 洪瑞敏 | 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 |
| CN110817925A (en) * | 2019-10-23 | 2020-02-21 | 江苏沙钢集团有限公司 | Method for resource utilization of desulfurized fly ash |
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