Method for promoting precipitation of calcium sulfate

Abstract

The invention discloses a method for promoting calcium sulfate precipitation, and belongs to the technical field of calcium sulfate scale treatment. The method for promoting calcium sulfate precipitation comprises the following steps: preparing the imidazolium ionic liquid additive; the method comprises the following steps: adding a NH4Cl solution into an imidazolium ionic liquid additive, and uniformly mixing to obtain an imidazolium ionic liquid + NH4Cl stock solution; the method comprises the following steps: adding CaSO4 into a stock solution of imidazolium ionic liquid and NH4Cl to prepare a mixed solution, uniformly mixing the mixed solution, and filtering the mixed solution; washing the calcium sulfate precipitate with water, and drying the calcium sulfate precipitate to obtain the calcium sulfate whisker. According to the method for promoting calcium sulfate precipitation, the imidazolium ionic liquid additive is added into the ammonium chloride solution, so that the solubility of calcium sulfate in the ammonium chloride solution is effectively reduced, and the purpose of removing calcium sulfate is achieved; and the calcium sulfate whisker is obtained by a hydrothermal method, so that the calcium sulfate crystal product is recycled, and the economic value is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of calcium sulfate scale treatment, and particularly relates to a method for promoting calcium sulfate precipitation. Background Art

[0002] In industrial production, the precipitation of CaSO 4 is complex because it has three crystal forms, namely gypsum (CaSO 4 ·2H 2 O), hemihydrate (CaSO 4 ·0.5H 2 O) and anhydrite (CaSO 4 ). Since the solubility of the three variants decreases with increasing temperature, CaSO 4 tends to precipitate from the solution onto the heat transfer surface to form scale. Different from calcium carbonate scale, calcium sulfate scale is hard in texture and dense in structure and cannot be directly dissolved by conventional inorganic acids such as hydrochloric acid. Calcium sulfate scale is considered to be one of the most difficult scales to remove. It can damage production equipment such as pumps, pipes, valves and heat exchangers. The deposits can also cause a reduction in equipment flow rate, corrosion, scaling, resulting in decreased efficiency, increased maintenance costs, and even equipment failure. If scale accumulates in the equipment, it may exacerbate blockage and increase the risk of pressure build-up.

[0003] In the ammonium chloride solution system, the ammonium chloride solution contains a certain amount of calcium sulfate. The calcium sulfate in the ammonium chloride solution is easily affected by temperature and forms calcium sulfate scale in pipes or equipment, affecting the normal operation of the equipment. Therefore, it is very important to effectively remove calcium sulfate from the ammonium chloride solution. Relying on temperature changes to achieve the crystallization of calcium sulfate has relatively low efficiency, and the removal efficiency of calcium sulfate is relatively low, and the generated scale is not conducive to recycling. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for promoting calcium sulfate precipitation. By adding an imidazole-based ionic liquid additive to the ammonium chloride solution, the solubility of calcium sulfate in the ammonium chloride solution is effectively reduced to achieve the purpose of removing calcium sulfate; and calcium sulfate whiskers are obtained by hydrothermal method, which is conducive to the recycling of calcium sulfate crystallization products and improves the economic value.

[0005] To achieve the above purpose, the present invention provides a method for promoting calcium sulfate precipitation, including the following steps: S1. Prepare an imidazole-based ionic liquid additive; S2. Add the NH 4 Cl solution to the imidazole-based ionic liquid additive and mix evenly to obtain a stock solution of imidazole-based ionic liquid + NH 4 Cl; S3. In the imidazole-based ionic liquid + NH4 Add CaSO to the stock solution of Cl 4 Prepare a mixed solution, mix the mixed solution evenly, and perform a filtration treatment on the mixed solution; obtain a filtrate and calcium sulfate precipitate S4. Wash the calcium sulfate precipitate and perform a drying treatment on the calcium sulfate precipitate to obtain calcium sulfate whiskers.

[0006] Preferably, in the step S1, the preparation method of the imidazole-based ionic liquid additive includes: S11. Add one or several of alkyl imidazole and halogenated hydrocarbon, halogenated alkyl acid, halogenated alkyl alcohol, metal salt solution to a solvent, and stir and react in an oil bath to obtain a reaction solution; S12. Filter the reaction solution, remove the solvent from the filtrate in a rotary evaporator to obtain an imidazole-based ionic liquid; perform vacuum drying on the imidazole-based ionic liquid to obtain an imidazole-based ionic liquid additive, and store the imidazole-based ionic liquid additive in a vacuum dryer using phosphorus pentoxide as a desiccant.

[0007] Preferably, in the step S11, the molar ratio of alkyl imidazole to halogenated hydrocarbon, halogenated alkyl acid, halogenated alkyl alcohol, metal salt solution is all 1:1.1.

[0008] Preferably, in the step S11, the alkyl group in the alkyl imidazole is one of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl.

[0009] Preferably, in the step S11, the halogen element in the halogenated hydrocarbon, halogenated alkyl acid, halogenated alkyl alcohol is one of chlorine, bromine, iodine; the hydrocarbon is an alkane; the alkyl group is one of ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl; the metal salt solution is one of metal sulfate, metal bisulfate, metal bisulfite, metal sulfite, metal acetate, metal tetrafluoroborate, metal hexafluorophosphate.

[0010] Preferably, in the step S11, the solvent is ethanol or toluene, the oil bath temperature is 30°C - 130°C, and the stirring time is 20h - 30h.

[0011] Preferably, in the step S12, the imidazole-based ionic liquid additive includes an imidazole-based cation and an anion. The imidazole-based cation is 1-alkyl-3-(alkyl carboxyl / alkyl hydroxyl) imidazole cation, where the alkyl is selected from one of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl; the alkyl carboxyl is selected from one of acetate, propionate, butyrate, valerate, and hexanoate; the alkyl hydroxyl is selected from one of ethanol, propanol, butanol, pentanol, and hexanol; the anion is selected from one of chloride ion, bromide ion, iodide ion, acetate ion, tetrafluoroborate ion, hexafluorophosphate ion, bisulfate ion, sulfate ion, sulfite ion, and bisulfite ion.

[0012] Preferably, in the step S2, the concentration of the imidazole-based ionic liquid additive is 5-15 wt%, and the concentration of the NH 4 Cl solution is 0.1 mol / kg - 0.5 mol / kg or 4.5 mol / kg - 5.0 mol / kg; in order to obtain a better scale removal effect, the concentration of the imidazole-based ionic liquid additive in the NH 4 Cl solution is 15 wt%.

[0013] Preferably, in the step S3, the mixing temperature of the mixed solution is 30°C - 50°C, the mixing and stirring speed is 30 rpm - 60 rpm, and the mixing and stirring time is 10 h - 15 h.

[0014] Preferably, in the step S4, the drying temperature is 40°C - 50°C, the drying time is 5 hours - 10 hours; the aspect ratio of the calcium sulfate whiskers is 1 - 100.

[0015] The advantages and positive effects of the method for promoting calcium sulfate precipitation according to the present invention are as follows: by adding an imidazole-based ionic liquid additive to the ammonium chloride solution, the solubility of calcium sulfate in the ammonium chloride solution is effectively reduced, the purpose of removing calcium sulfate is achieved, and the problem of scale formation of calcium sulfate in the pipeline is alleviated; and calcium sulfate whiskers are obtained by the hydrothermal method, which is conducive to the recycling and utilization of calcium sulfate crystallization products and improves the economic value.

[0016] The HSO in the imidazole bisulfate ion liquid 4 - and the SO in calcium sulfate 4 2- produce a common ion effect, and HSO 4 - dissociates to produce SO 4 2- , increasing the SO in the solution 4 2-The concentration inhibits the dissolution of calcium sulfate, leading to a decrease in its solubility. The addition of imidazole-based ionic liquids also changes the physicochemical properties of the solution such as density, sound velocity, and isentropic compressibility. These property changes affect the solubility of calcium sulfate, that is, the addition of imidazole-based ionic liquids increases the ionic strength of the solution, resulting in an enhanced polarity of the solution, thereby reducing the solubility of calcium sulfate. In addition, the interaction between imidazole-based ionic liquids and water disrupts the hydrogen bond structure of water, reducing the solvation ability of water molecules for calcium sulfate and further decreasing the solubility of calcium sulfate.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the XRD pattern of the calcium sulfate whiskers prepared; Figure 2 is the solubility of calcium sulfate in ammonium chloride solution in different ionic liquids with a mass percentage of 15% in the present invention; Figure 3 is the solubility of calcium sulfate in ammonium chloride solution in different ionic liquids with a mass percentage of 10% in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. In case of inconsistency, the meaning stated in this specification or the meaning derived from the content recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application. For the purpose of accurately describing the technical content in this application and for accurately understanding the present invention, the following explanations or definitions are given to the terms used in this specification before describing the specific embodiments: Example 1 S1. Prepare an imidazole-based ionic liquid additive.

[0020] Methylimidazole and bromoethane were added to a round-bottom flask at a molar ratio of 1:1.1 and stirred continuously at 130 °C for 24 hours to obtain 1-ethyl-3-methylimidazolium bromide ionic liquid. The 1-ethyl-3-methylimidazolium bromide ionic liquid and saturated sodium bisulfate solution were added to a round-bottom flask at a molar ratio of 1:1.1, using ethanol as a solvent, and reacted under a 70 °C oil bath and continuous stirring for 24 hours. After the reaction, the precipitated NaBr by-product was filtered, the solvent in the filtrate was removed by a rotary evaporator, and the obtained ionic liquid was dried under vacuum and stored in a vacuum desiccator with phosphorus pentoxide as a desiccant.

[0021] S2. Add NH 4 Cl solid to the aqueous solution of 1-ethyl-3-methylimidazolium hydrogensulfate ionic liquid to prepare a diluted stock solution of [C 2 mim]HSO 4 +NH 4 Cl, with the concentration of NH 4 Cl being 0.2 mol / kg and the concentration of the ionic liquid being 15 wt%.

[0022] S3. Add the diluted stock solution of [C 2 mim]HSO 4 +NH 4 Cl to an excess of CaSO 4 to prepare a mixed solution, and oscillate the mixed solution at 40 rpm and 30 °C for 12 h. After filtration, the filtrate is centrifuged at 3500 rpm (REMI R-8M) for 10 min.

[0023] S4. Wash the calcium sulfate precipitate obtained by filtration three times with water, place the solid in a blast drying oven, dry it at 45 °C for 8 h, and after the product is dried to a constant weight, calcium sulfate solid is obtained.

[0024] Take the supernatant after filtration and obtain the solubility of calcium sulfate in the solution as 0.0061 mol / kg by the EDTA titration method. The separated calcium sulfate is analyzed by X-ray diffraction and scanning electron microscopy, and it is calcium sulfate dihydrate whiskers with an average aspect ratio of 63.

[0025] Example 2 S1. Prepare an imidazole-based ionic liquid additive.

[0026] Add methylimidazole and chlorobutane to a round-bottom flask at a molar ratio of 1:1.1, and continuously stir at 130 °C for 24 hours to obtain 1-butyl-3-methylimidazolium chloride ionic liquid. Add the 1-butyl-3-methylimidazolium chloride ionic liquid and saturated sodium bisulfate solution to a round-bottom flask at a molar ratio of 1:1.1, use ethanol as the solvent, and react at 70 °C in an oil bath with continuous stirring for 24 hours. After the reaction, filter out the by-product NaCl precipitate, remove the solvent from the filtrate in a rotary evaporator, and obtain the ionic liquid by vacuum drying, and store it in a vacuum desiccator with phosphorus pentoxide as the desiccant.

[0027] S2. Add NH 4 Cl solid to the aqueous solution of 1-butyl-3-methylimidazolium hydrogensulfate ionic liquid to prepare a diluted stock solution of [C 4 mim]HSO 4 +NH 4 Cl, with the concentration of NH 4 Cl being 0.5 mol / kg and the concentration of the ionic liquid being 10 wt%.

[0028] S3. Add the diluted stock solution of [C 4 mim]HSO 4 +NH 4 Cl to an excess of CaSO 4 to prepare a mixed solution, and shake the mixed solution at 30 rpm and 40 °C for 12 h. After filtration, the filtrate is centrifuged at 3000 rpm (REMI R-8M) for 10 min.

[0029] S4. Wash the calcium sulfate precipitate obtained by filtration three times with water, place the solid in a blast drying oven, and dry it at 45 °C for 8 h. After the product is dried to a constant weight, calcium sulfate solid is obtained.

[0030] Take the supernatant after filtration and obtain the solubility of calcium sulfate in the solution as 0.012 mol / kg by EDTA titration method. The separated calcium sulfate is analyzed by X-ray diffraction and scanning electron microscopy, and it is calcium sulfate dihydrate whiskers with an average aspect ratio of 51.

[0031] Example 3 S1. Prepare an imidazole-based ionic liquid additive.

[0032] Add methylimidazole and 3-bromo-1-propanol to a round-bottom flask at a molar ratio of 1:1.1, use toluene as a solvent, and stir continuously at 80 °C in an oil bath for 24 hours to obtain 1-methyl-3-propanol imidazole bromide ionic liquid. Rotate to remove the solvent in a rotary evaporator, and the obtained ionic liquid is dried under vacuum and stored in a vacuum dryer with phosphorus pentoxide as a desiccant.

[0033] S2. Add NH 4 Cl solid to the aqueous solution of 1-methyl-3-propanol imidazole bromide ionic liquid to prepare a diluted stock solution of 1-methyl-3-propanol imidazole bromide + NH 4 Cl, with the concentration of NH 4 Cl being 4.5 mol / kg and the concentration of ionic liquid being 15 wt%.

[0034] S3. Add the diluted stock solution of 1-methyl-3-propanol imidazole bromide + NH 4 Cl to an excess of CaSO 4 to prepare a mixed solution, and shake the mixed solution at 60 rpm and 50 °C for 12 h. After filtration, the filtrate is centrifuged at 3000 rpm (REMI R-8M) for 10 min.

[0035] S4. Wash the calcium sulfate precipitate obtained by filtration three times with water, place the solid in a blast drying oven, and dry it at 45 °C for 8 h. After the product is dried to a constant weight, calcium sulfate solid is obtained.

[0036] The solubility of calcium sulfate in the solution was obtained as 0.007 mol / kg by the EDTA titration method for the filtered supernatant. The separated calcium sulfate was analyzed by X-ray diffraction and scanning electron microscopy, and it was calcium sulfate dihydrate whiskers with an average aspect ratio of 55.

[0037] Example 4 S1. Prepare an imidazole-based ionic liquid additive.

[0038] Methylimidazole and chlorobutane were added to a round-bottom flask at a molar ratio of 1:1.1, and stirred continuously at 130 °C for 24 hours to obtain 1-butyl-3-methylimidazolium chloride ionic liquid. 1-Butyl-3-methylimidazolium chloride ionic liquid and saturated sodium bisulfite solution were added to a round-bottom flask at a molar ratio of 1:1.1, using ethanol as a solvent, and reacted for 24 hours under the conditions of an 80 °C oil bath and continuous stirring. After the reaction, the precipitated NaCl by-product was filtered, the solvent in the filtrate was removed by a rotary evaporator, and the obtained ionic liquid was dried under vacuum and stored in a vacuum desiccator with phosphorus pentoxide as a desiccant.

[0039] S2. NH 4 Cl solid was added to the aqueous solution of 1-butyl-3-methylimidazolium bisulfite ionic liquid to prepare a diluted stock solution of [C 4 mim]HSO 3 +NH 4 Cl, with the NH 4 Cl concentration of 5.0 mol / kg and the ionic liquid concentration of 10 wt%.

[0040] S3. The diluted stock solution of [C 4 mim]HSO 3 +NH 4 Cl was added to an excess of CaSO 4 to prepare a mixed solution, and the mixed solution was oscillated at 30 rpm and 40 °C for 12 h. After filtration, the filtrate was centrifuged at 3000 rpm (REMI R-8M) for 10 min.

[0041] S4. The calcium sulfate precipitate obtained by filtration was washed 3 times with water, and the solid was placed in a blast drying oven and dried at 45 °C for 8 h. After the product was dried to a constant weight, calcium sulfate solid was obtained.

[0042] The solubility of calcium sulfate in the solution was obtained as 0.0091 mol / kg by the EDTA titration method for the filtered supernatant. The separated calcium sulfate was analyzed by X-ray diffraction and scanning electron microscopy, and it was calcium sulfate dihydrate whiskers with an average aspect ratio of 43.

[0043] Example 5 S1. Prepare an imidazole-based ionic liquid additive.

[0044] N-butylimidazole and 4-bromobutyric acid were added to a round-bottom flask at a molar ratio of 1:1.1, and toluene was used as the solvent. The mixture was continuously stirred at 120 °C for 24 hours to obtain 1-butyl-3-propylcarboxylimidazolium bromide ionic liquid. The solvent was removed by rotary evaporation, and the obtained ionic liquid was dried under vacuum and stored in a vacuum desiccator with phosphorus pentoxide as the desiccant.

[0045] S2. NH 4 Cl solid was added to the aqueous solution of 1-butyl-3-propylcarboxylimidazolium bromide ionic liquid to prepare a diluted stock solution of 1-butyl-3-propylcarboxylimidazolium bromide + NH 4 Cl, with the concentration of NH 4 Cl being 0.1 mol / kg and the concentration of the ionic liquid being 15 wt%.

[0046] S3. The diluted stock solution of 1-butyl-3-propylcarboxylimidazolium bromide + NH 4 Cl was added to an excess of CaSO 4 to prepare a mixed solution, and the mixed solution was oscillated at 40 rpm and 30 °C for 12 h. After filtration, the filtrate was centrifuged at 3000 rpm (REMI R-8M) for 10 min.

[0047] S4. The calcium sulfate precipitate obtained by filtration was washed three times with water, and the solid was placed in a blast drying oven and dried at 45 °C for 8 h. After the product was dried to a constant weight, calcium sulfate solid was obtained.

[0048] The supernatant after filtration was taken, and the solubility of calcium sulfate in the solution was obtained by EDTA titration method as 0.007 mol / kg. The separated calcium sulfate was analyzed by X-ray diffraction and scanning electron microscopy, and it was calcium sulfate whiskers with an average aspect ratio of 31.

[0049] The separated crystals were subjected to XRD testing, as Figure 1 shown. It can be determined from the XRD pattern that the obtained whiskers are calcium sulfate whiskers.

[0050] As Figure 2 , Figure 3 shown. The solubility of CaSO 4 in 0 - 5.5 mol / kg NH 4 Cl solution shows a trend of first increasing and then decreasing with the increase of the molar concentration of NH 4 Cl solution. When the molar concentration of NH 4 Cl solution is 2.75 mol / kg, the solubility of CaSO 4 is the largest, which is 0.0158 mol / kg. In NH 4When the molar concentration of the Cl solution is 0.1 mol / kg - 0.5 mol / kg and 0.45 mol / kg - 0.5 mol / kg, the solubility of CaSO 4 is maximally 0.0128 mol / kg. It can be seen that after adding imidazole-based ionic liquid additives to the NH 4 Cl solution, the solubility of CaSO 4 in the NH 4 Cl solution is significantly reduced, which can effectively promote the precipitation of CaSO 4 and thus reduce the content of CaSO 4 in the NH 4 Cl solution, alleviating the formation of water scale by CaSO 4 in the pipeline.

[0051] Therefore, by adopting the method for promoting calcium sulfate precipitation described in the present invention, by adding imidazole-based ionic liquid additives to the ammonium chloride solution, the solubility of calcium sulfate in the ammonium chloride solution is effectively reduced, achieving the purpose of removing calcium sulfate; and calcium sulfate whiskers are obtained by the hydrothermal method, which is conducive to the recycling and utilization of calcium sulfate crystallization products and improves the economic value.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for promoting calcium sulfate precipitation, characterized in that, The following steps are involved: S1, preparing imidazole ionic liquid additives; S2, adding NH4Cl solution to the imidazole ionic liquid additive, mixing evenly, to obtain a stock solution of imidazole ionic liquid + NH4Cl; S3, adding CaSO4 to the original solution of imidazole ionic liquid + NH4Cl to prepare a mixed solution, mixing the mixed solution evenly, and filtering the mixed solution; A filtrate and calcium sulfate precipitate were obtained. S4, washing the calcium sulfate precipitate with water, and drying the calcium sulfate precipitate to obtain calcium sulfate whiskers.

2. A method for promoting calcium sulfate precipitation according to claim 1, characterized in that, In S1, the preparation method of the imidazole ionic liquid additive comprises: S11, adding alkyl imidazole and one or more of halogenated hydrocarbon, halogenated alkyl acid, halogenated alkyl alcohol, and metal salt solution to a solvent, stirring and reacting in an oil bath to obtain a reaction solution; S12, filtering the reaction solution, removing the solvent from the filtrate in a rotary evaporator to obtain an imidazole ionic liquid; vacuum drying the imidazole ionic liquid to obtain an imidazole ionic liquid additive, and storing the imidazole ionic liquid additive in a vacuum dryer using phosphorus pentoxide as a desiccant.

3. A method for promoting calcium sulfate precipitation according to claim 2, characterized in that: In the S11, the molar ratio of alkyl imidazole to halogenated hydrocarbon, halogenated alkyl acid, halogenated alkyl alcohol and metal salt solution is 1:1.

1.

4. A method for promoting calcium sulfate precipitation according to claim 3, characterized in that: In S11, the alkyl group in the alkylimidazole is one of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl.

5. A method for promoting calcium sulfate precipitation according to claim 3, characterized in that: In S11, the halogen element in the halogenated hydrocarbon, halogenated alkyl acid, and halogenated alkyl alcohol is one of chlorine, bromine, and iodine; the hydrocarbon is an alkane; the alkyl is one of ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl; and the metal salt solution is one of metal sulfate, metal hydrogen sulfate, metal hydrogen sulfite, metal sulfite, metal acetate, metal tetrafluoroborate, and metal hexafluorophosphate.

6. A method for promoting calcium sulfate precipitation according to claim 2, characterized in that: In the S11, the solvent is ethanol or toluene, the oil bath temperature is 30° C.-130° C., and the stirring time is 20 h-30 h.

7. A method for promoting calcium sulfate precipitation according to claim 2, characterized in that: In S12, the imidazolium ionic liquid additive includes an imidazolium cation and an anion, the imidazolium cation is a 1-alkyl-3-(alkyl carboxyl / alkyl hydroxyl) imidazolium cation, the alkyl group is selected from one of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl, the alkyl carboxyl group is selected from one of acetic acid, propionic acid, butyric acid, pentanoic acid, and hexanoic acid; the alkyl hydroxyl group is selected from one of ethanol, propanol, butanol, pentanol, and hexanol; the anion is one of chloride, bromide, iodide, acetate, tetrafluoroborate, hexafluorophosphate, hydrogen sulfate, sulfate, sulfite, and hydrogen sulfite.

8. A method for promoting calcium sulfate precipitation according to claim 1, characterized in that, In S2, the concentration of the imidazole ionic liquid additive is 5-15wt%, and the concentration of the NH4Cl solution is 0.1mol / kg-0.5mol / kg or 4.5mol / kg-5.0mol / kg; preferably, in order to obtain a better descaling effect, the concentration of the imidazole ionic liquid additive in the ammonium chloride solution is 15wt%.

9. A method for promoting calcium sulfate precipitation according to claim 1, characterized in that, In S3, the mixing temperature of the mixed liquid is 30°C-50°C, the mixing speed is 30rpm-60rpm, and the mixing time is 10h-15h.

10. A method for promoting calcium sulfate precipitation according to claim 1, characterized in that: In S4, the drying temperature is 40° C.-50° C., the drying time is 5 hours-10 hours; and the aspect ratio of the calcium sulfate whisker is 1-100.

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